The Grand Prix FAQ

Everything you need to know about your Grand Prix...

WARNING: Some of these items are not legal or advised; they exist here for learning purposes only. Make sure you know what you are doing before attempting to implement or try anything discussed here. These are not suggestions, they are only questions and answers. We are not responsible for the accuracy or use of this information; please use this information at your own risk.

There are a few different sections here. Pick the section you would like to read through from the following selections:

• Before I Buy a Grand Prix
• In General
• Common Misconceptions
• Upgrades

Before I Buy a Grand Prix

I just ordered a Grand Prix from my dealer. They told me I'd be waiting for six to eight weeks for it to arrive, but I've heard otherwise. Can you explain how the ordering process works, and what I can expect to happen from here? How long can I realistically expect to wait, and what do the terms "preferenced" and "on restriction" mean?

When you go to your dealer to order a car, you pick from a series of options. Once the dealer knows exactly what you want, he goes to the computer and builds out your car. The order then sits in a queue at the dealership waiting to be acknowledged or pulled by Pontiac. Every week, Pontiac pulls a group of orders. In other words, Pontiac may pull orders for GT coupes in a block, SE coupes in another, and GT sedans in another because they build cars with similar features in groupings. So if you place your order for a GT sedan (or GTP) right after they just pulled a bunch of GT sedan orders, you might have to wait until they start pulling GT sedan orders again. When the order is pulled from Pontiac, it is preferenced and assigned a build week. That means that your car will be built. The build week is usually 4 to 6 weeks after the preference date. The build week is the week that your car will be completed, and once it is completed, it is usually shipped the next day. Shipping takes 10 to 14 working days (including Saturdays), so the actual arrival date could be around 2 to 3 weeks after the build week.

Order times are highly dependent on the dealer's allocation with Pontiac and the options you choose. The dealer's allocation is based on how many cars they sold during the previous quarter. So if you go to a smaller dealer who doesn't sell many cars, they may not have a high allocation, and thus it might take longer to get your car. Also, some of the options you chose may be on restriction. Restriction means that dealers are only allowed to order a certain number of cars with that option. The three options that seemed to have cause the most delay and that have been on restriction many times for long durations are the sunroof, the high polished wheels, and the dual-zone air conditioning. So if a couple of people ordered the same model (at the same dealership as you) with the sunroof before you, you are going to have to wait longer, because your dealer may only be allowed to order one GP with a sunroof per week.

Finally, anyone who orders around Christmas should be aware that GM shuts down for 2 weeks which can also add a delay to the order process.

Basically, most people who end up waiting 3 or 4 (and sometimes 5) months most likely have a dealer who could not place their order for 1 to 2 months after they requested or have ordered option(s) that were on restriction. There are some people who have received their cars 6 to 8 weeks after they ordered them, so it can happen, but just don't bet on it. Go into the waiting period expecting the car in 12 to 14 weeks, and you probably won't be disappointed.

One more thing. Ask the sales person to check the computer for dealers inventory. Your exact car may already exist on another dealers lot. Dealers often trade cars with other dealers in the area and will be more than happy to have your car delivered from 200 or 300 miles away (or more) to get the sale. The same dealer prep is done when you car arrives at your dealer and there should be no additional charge.

How much over dealer invoice should I expect to pay for my new Grand Prix?

From what we know, people have paid anywhere from around $200 to upwards of $1000 or more above dealer cost for their Grand Prix. If you order, you are more likely to be able to strike a bargain than if you want to buy off the lot, although this seems to be changing. Definitely don't pay sticker price for the car, and if you're not in a hurry then I would suggest ordering your car (from a company like ACS which charges a flat $275 fee above dealer cost) with exactly the options you want. To make sure you know how much the car should cost you and how much each option adds to the bottom line, check out sites like Edmund's which tells you both the sticker (MSRP) and dealer (invoice) cost of the car. To figure out how much to pay, add the base dealer price to the dealer cost of the options and delivery charge and then add a few hundred dollars. Don't let a dealer make you believe that he is only making a few hundred dollars on the car, because he is making that money plus a holdback of about 3% (for Pontiacs). This means he is actually making well over a thousand dollars off the sale, even if he sells to you at cost! Read about holdbacks on the Edmund's site.

Another trick that seems to work more and more these days is to e-mail your dealer with an offer. You can get alot of inside information as to what the current 'deals' are and where you stand with your mission and remain basically anonymous.

Bottom line: I would suggest offering no more than $500 over dealer cost, and less is always better.

I'll be picking up my Grand Prix from the dealer soon. Is there anything in particular that I should check or ask for before taking delivery of the vehicle?

Dressing the wheels may mean that you will experience the dreaded yellow spots on your car. This is especially noticeable on white cars. Ask the dealer not to dress the tires - you can do it yourself using your favorite tire dressing after you've picked up the car.

I know that I can order a sunroof from the factory, but some say it opens into the roof and other say it sits on top of the roof like a spoiler. Which is correct, and is it see-through (made of glass) or solid? What if I don't want to wait the extra time because the sunroof is on restriction? Are there alternatives?

The factory sunroof (referred to as a "spoiler" type sunroof) does not retract into the roof of the car. Rather, it slides along a track and sits at about a 10 degree angle over the roof of the car. To some owners, this type of roof is undesirable because of appearance, wind noise, potential damage to the glass from rocks, and a smaller opening. The roof is made of glass and has a retracting sunshade. Some people also refer to the glass with sunshade roof as a moonroof. The spoiler roof has the express open feature, and the venting feature as well.

Many buyers opt to purchase or order their Grand Prixs without the sunroof, and have the car sent out for an aftermarket sunroof for either one or both of the following reasons: 1) they don't want a spoiler type sunroof and 2) they don't want to wait the extra time it takes to order the factory sunroof due to restrictions. There are several aftermarket sunroof companies, but the most well known and recommended company is the American Sunroof Company, or ASC. They have a website with more information. They have pictures of the Grand Prix with the ASC sunroof model 750VSS (VSS stands for venting, sliding sunroof). However, some people have been able to get the ASC model 925VSS, which is a larger sunroof. The ASC sunroofs come with the extra feature of closing automatically when you shut off the car, and they retract into the roof. The trade-off is that in order for the sunroof to retract into the roof, because of the curvature of the roof, you lose approximately 2-3 inches of headroom. This can be a significant impact for drivers and passengers over 6 feet tall or with long torsos. The aftermarket sunroof with installation should cost you around $1000 - don't let your dealer convince you that you have to pay more because that means he is imposing a mark-up on the feature. You can call ASC to get the actual price and the nearest installer. Installation time is usually about one day.

If you are sending your Grand Prix to SLP for the GTX package, they offer installation of the Webasto spoiler type sunroof for $799. This is $292 above the invoice price for the factory sunroof, and it doesn't have any extra features. Some people have questioned the quality of the Webasto roofs as well. The only advantage to having the sunroof installed at SLP is avoiding potential ordering delays, since the sunroof is often on restriction from the factory.

In General

I heard that I can disable the Daytime Running Lamps (DRLs) in my Grand Prix. Why would I want to do this and how would I do it (this is not recommended)?

If you want to disable the DRLs but not the automatic headlights, unplug the voltage reducing diode in the DRL circuit. It is a large, finned object located on the outer wall on the left side under the dash. It is visible through the small access panel the you can see when the driver's door is open. If you unplug this diode, you will turn off the DRLs and not affect anything else. If you do not wish to have the automatic headlamps or DRLs active, simply pull the appropriate fuse in the fuse block located to the right of the glove box. Remember, though, that you may be eligible for a discount on your insurance premium for having and using DRLs and they are meant as a safety feature so that other drivers will see you more easily. They aren't cool, but they could save you and your shiny new GP from getting into a mishap.

Why does my "Low Fuel" warning light come on when I've only used 13 or 14 gallons of gas (according to my Driver Information Center)?

This is a safety feature. GM does not want owners waiting until they are "riding on fumes" to fill up. Although your tank holds 18 gallons, waiting until you have only half a gallon left is not a good idea. Also, the Driver Information Center (DIC) is not as accurate when you get to about 13.5 gallons, so don't trust the reading as gospel. It is the opinion of many GP owners that GM has made this feature read correctly until you get below a half tank at which point the reading begins becoming biased by a "fudge factor" so that you are kept from driving too far with little fuel. Many owners do not like this and wish GM would simply allow the owner to decide when to put in fuel based on an accurate reading, which is not available. Take this as you will.

Where can I buy a Grand Prix GPX? What about a GTX? An F.1? What is the difference between these three and my GT or GTP?

You can't buy a GPX. This was a prototype vehicle shown by Pontiac at the 1995 Auto Shows. You can buy a GTX from Pontiac in select markets. The GTX is a special add-on package for SE, GT, and GTPs that adds a functional ram air hood as well as other options. Check with your dealer for availability. Pricing and details are available on SLP web site. The F.1 is a super-high-end packaged designed for the true enthusiast. Power upgrades and appearance upgrades including a functional ram-air hood, functional rear wing, larger wheels and tires, and much more were available until the end of 1998, when MPD was shut down.

Sometimes when it's raining and I haven't used the brakes in a while they won't work right away if I go to use them. Why is this? What can I do about it?

This is most common on Grand Prixs equipped with the 5-spoke wheel design, but has been known to happen with custom wheels as well with differing severity and frequency. With the rim having such a large opening, it allows the water to saturate the brakes and rotors. The brakes must then shed the water between the rotor and the pad before they will work properly. You may hear about wheel covers (a plastic disc which mounts behind the rim on the rotor bolt pattern). But, while this will help reduce the water it can also reduce air flow to and from the brakes which could cause the rotors to warp. Another option is aftermarket performance rotors which have holes on the face of the rotor (called cross-drilled rotors) or grooves (called slotted rotors) to allow the water to disperse properly. At any rate, when driving in the rain it is a good idea to use your brakes every once in a while to make sure they don't fail on you when you need them in an emergency.

Why does my coupe's passenger seat not lock into a vertical position? Is this a design flaw?

The seat is locked by an inertial mechanism. What this means in English is that the engineers who designed the seat thought it would be nice to be able to push the seat forward with little effort, and so the seat back does not lock unless you brake very hard and the nose of the car dives to a certain angle which triggers the seat back to lock. Contrary to many people's beliefs, this is not a design flaw, and was meant to act in this manner.

Why does the air conditioner light stay on in my dual-zone equipped Grand Prix when it's 40 degrees outside?

The automatic climate control system strives to keep a constant, comfortable temperature and humidity level inside the car. This has the added benefit of reducing inside window fogging. The air conditioner is designed to run on dual-zoned cars at any temperature above 37 degrees F. On previous GM cars, the A/C light stayed on even when the air conditioner was disabled due to low outside temperatures. Owners and service departments bombarded GM with questions about this, so now the air conditioner light goes out when the A/C is disabled due to low ambient air temperatures. Finally, if you do decide to use the automatic feature, just set it and forget about it. It is not necessary or even a good idea to set it lower or higher because of extreme temperatures outside. In other words, if it is 95 outside, it will not cool the car any faster if you set the climate control to 65 instead of 70. If 70 is what you want, then set it to 70.

The traction control system (TCS) on my 1997-2001 Grand Prix doesn't seem to work like I think it should. How is it supposed to work?

The ABS kicks in first, and if the ABS is not effectively reducing wheel spin, the PCM reduces engine torque by pulling spark. There are 7 modes of TCS, and as wheelspin continues, additional modes are activated, each with increasing spark reduction. As a last resort, injectors are turned off in a certain pattern. The low traction indicator only comes on when wheel spin occurs and not when the TCS is activated.

What is that small thing that looks like a marble in the middle of my dashboard? What's the other little thing that looks like a hole right next to it?

The marble-looking thing is a sun sensor used by the automatic climate control system to increase fan speed and compressor time when the sun is heating the cabin of the car. Inside the hole is a light sensor used to operate the automatic headlight control. When low levels of light are detected, the headlights automatically illuminate.

It seems every time I drive my car I get a new paint chip in the hood or front fascia. What can I do to protect my car?

This is a common problem due to the sloping grade of the hood. Some recommendations from other owners are hood covers, bras, bug deflectors and clear plastic adhesives made by such companies as 3M. If you get a bra, remember to take it off after it rains and before a car wash. Road grime, sap, dirt and miscellaneous debri get trapped underneath and could ruin the finish of your hood.

I've heard that there are some different types of shop manuals for the Grand Prixs. Why would I want to own a shop manual in the first place, and which kind should I buy?

There is a set of three large books by Helm Publications which detail (and I mean detail) everything about your Grand Prix. Usually a company called Chilton's writes manuals, but these are skimpy on details and do not suffice for do-it-yourselfers to get any real work done on their cars. I highly suggest the Helm manuals; they are the same manuals used by your Pontiac service department when you get your vehicle serviced, and are the official GM repair and maintenance manuals. Helm can be reached at 1-800-782-4356.

The other day I was driving very fast, and once I hit a certain speed my car seemed to just cut off and didn't let me go any faster. What happened? Do I have a problem with my car?

All Grand Prixs are equipped with a speed limiter that will retard the fuel delivery to your engine at a pre-set speed (108 for normally aspirated 3800's and 126 for supercharged 3800's). This will prevent the car from exceeding the speed limitation of the factory tires' speed rating. This operation was designed by car manufactures to prevent lawsuits and dangerously high speeds, and will not harm your Grand Prix.

I have a GTP and it has a selection for "Performance Shift." What does it do, and in what driving situations would I want to use it?

Putting your GTP into "Performance Shift" mode raises the RPM level at which the transmission shifts into the next highest gear, and may allow your RPMs to go a bit higher than in normal mode. Use it for getting up to speed more quickly, passing (except when in 4th gear; it won't help here), racing, etc. According to those more sensitive to the shift characteristics, "Performance Shift" mode feels quite a bit more firm and quick during shifts than normal mode.

A friend said I should use synthetic motor oil in my car for better performance and protection. Will I see a performance difference with the synthetic oil? Should I use it anyway?

While synthetic oil will probably not increase your car's performance, it will protect and retain its viscosity better than standard oil. It is up to you whether this benefit is worthy of the cost delta. The owner's manual states that only standard oil with the starburst symbol of approval (found on all major brands) is required to maintain warranty coverage. Some people believe that the higher temperatures generated due to a supercharger (or turbocharger) warrant using better oil such as synthetic. Standard oil tends to break down at lower temperatures than synthetic oil and is believed to help during cold starts. For more info., check out Ed Hackett's excellent oil FAQ, posted irregularly on the Usenet newsgroups rec.motorcycles and rec.autos.tech.

If I had a problem with my old car, I could check a list of Technical Service Bulletins (TSBs) for a mention of the problem which told the dealer what it might be. This car is very new, and I can't find a TSB listing for it. Can you help me?

Alldata maintains a list of TSBs for all cars, however their online list is not always complete. Check it often for details. However, in the event you have a problem, check with your dealer who always has a list of the lastest TSBs.

Someone told me that my tank holds 15 gallons of gasoline. Another person told me it was 18 gallons. Who's right?

The person who told you it holds 18 gallons is correct. This applies to 1997 and 1998 cars. Apparently Pontiac changed this for 1999; the new capacity is 17 gallons.

Is there something I can use to get defects out of my paint? What should I use to polish the car afterward?

According to many users, products like ClayMagic (use the blue clay only) really help remove surface contaminants (including rail dust and acid rain defects) from the clearcoat of your Grand Prixs paint. After using the clay on the surface of your car (make sure to read the directions thouroughly before starting), many owners prefer to use Zaino Bros. Show Car Polish products to protect the newly-cleaned surface. They are easy to apply, remove, and last longer and resist dust more than other brands.

How do I reset the tire pressure warning system on my Grand Prix?

As stated in the owner's manual, there is a yellow button underneath the dashboard to the right of the steering wheel. Depress the button for a few seconds to reset the warning.

Someone challenged me to a race. He has a 19xx (Make) (Model). Am I gonna get my butt kicked?

This depends on so many factors it can't be discussed without a lengthy discussion. Weather, car, manufacturing tolerances, weather, launch, conditions, and more all come into play when discussing who will win a race. You simply can't tell by looking at the "published numbers" for horsepower, torque, weight, and performance to compare. Your friend may have a modified car, you may have a modified car, the race may take place at high speeds or low speeds, in a straight line or around curvy roads, etc.

Common Misconceptions

Do I really need to use premium gasoline in my GTP? Can't I just use regular?

Yes, you really do need to use premium (defined in the owner's manual as 91 octane or above) fuel in your GTP. This is because the higher output of the engine using the compressed air from the supercharger will be more prone to detonation (premature ignition of the air/fuel mixture) than a similar normally aspirated engine. Higher octane fuels prevent detonation and knock. In extreme cases you may use regular octanes, but do not do so for long.

I know that Pontiac specified the fuel economy of my car, but I've been getting lower or higher than their numbers. Why?

As with any vehicle, your fuel economy varies with driving conditions and habits. If you travel hilly roadsides you will get fewer miles per gallon than someone who travels on flat roads. If you accelerate with a heavy right foot, you will get fewer miles per gallon than someone who lightly taps the gas pedal.

Upgrades

What is a K&N filter and why is everyone talking about it? Do I need one for my Grand Prix?

K&N is an aftermarket manufacturer of air filters for your car. The air filters from K&N provide higher flow (and thus increased power, although maybe not noticeably) of air to your engine. The more air your engine has to use, the more power it will output. You don't necessarily need one for your Grand Prix, but it's not a bad idea. The filter is re-useable and can simply be cleaned and put back in (as opposed to paper filters like your stock filter that must be discarded at certain intervals). Also, some studies have shown K&N filters to be more efficient filters (that is, they filter better than paper OEM-style filters). You can buy a K&N filter at most large auto parts store.

I keep hearing about getting a ram-air hood and intake for my late-model Grand Prix. Where can I order from? Does the hood increase my horsepower?

There are currently three known companies that make ram-air hoods for the Grand Prix. They are as follows (see the websites for details):

Do any companies make an aftermarket chip for my Grand Prix?

No. Unlike older cars, newer cars don't use replaceable chips. Instead, they have ECUs (electronic control units) or PCMs (powertrain control modules) that must be reprogrammed with a special unit. Hypertech is an example of a company that makes such a unit, but as of now there are none available for W-body Grand Prixs. Dennis Mecham does PCM reprogramming for a hefty charge ($400 plus a possible $50 net core charge which is non-refundable). It has been shown that horsepower is barely changed when moving to this re-calibration of the PCM. Other things are affected (some might argue that they are negatively affected) but the overall driveability is, in many owner's opinions, warranted. But most agree that the cost of doing this outweighs its benefits.

I keep hearing a discussion on a smaller pulley for my supercharger (GTP only). What will this buy me and should I go ahead and put one on? How much will it cost me? Will this void my warranty?

You can upgrade your pulley with three different sizes: 3.4 inch, 3.5 inch, and 3.6 inch.
The stock pulley on a GTP's supercharger, which is an Eaton Model 90, measures 3.8 inches in diameter. This turns the supercharger at a rate of 7 divided by 3.8 (or 1.842) times the speed of the crankshaft, which in the case of wide open throttle (WOT) at 6,000 RPM (assuming redline at 6,000 RPM which does not happen in a GTP with stock PCM calibrations) which is 11,050 RPM. This rotation of the supercharger pulley drives two impellers that compress the air from the intake and throttle body and force it into the lower intake manifold as compressed air.

If a smaller pulley than 3.8 inches is used, you increase the rate at which the pulley turns and thus increase the compression of the air that's taking place inside your supercharger, called boost. Your stock pulley will translate into a maximum of about 7.5 to 8 pounds per square inch (psi) of boost, whereas a 3.5" pulley will increase that to over 11 psi of boost. In terms of power output you can expect around 30 more horsepower and at least the same amount of torque, a noticeable difference in power.

Be warned, though: this upgrade voids your powertrain warranty and puts your drivetrain at a higer risk of damage. Take proper precautions such as installing a transmission cooler, synthetic transmission fluid, and anything else that will help your car stay strong.

Another product you can use to increase boost in the same manner is a Magnuson nose drive. This upgrade, however, assumes mechanical abilities in that you must remove several components, including the supercharger, to upgrade the pulley. But the benefit to using a Manguson nose unit is that the pulley is then easy to swap out in the future: just loosen a nut and take off the pulley. Different sizes are available for this unit, right now 3.4" and 3.6" are the most popular. Anything less than 3.4" will require reprogramming of the PCM (according to Magnuson) to take advantage of the additional power. If programming is not available and you use a smaller diameter pulley, the PCM will sense knock and detonation and decrease spark timing such that the power output of the engine might actually be less than with a larger pulley. Be very careful!

So if I want better handling, can I install lowering springs? Why did someone tell me not to because I would have a power steering pump problem if I did so? What can I do about this problem? Do I need upgraded struts in order to do this upgrade?

In most owner's opinions this is true. After installing these springs (which work with the stock struts, wheels, etc.) a noticeable difference in cornering can be felt. The car no longer leans excessively on sharp turns but does ride a bit more harshly over bumpy ground. When driving over a large bump, the car will jolt skyward but will return to normal ride position immediately. They take some getting used to, but are well worth it if you're a hard core driver.

What are some ways I can get more power and performance out of my car? Where can I find more information on these and other upgrades?

In general, to increase the output power on any vehicle you should first look at optimizing the intake of air and the exhaust of gases from the engine. Once these have been dealt with, add-on performance items such as superchargers or turbochargers will be the best improvement in output power that you can get. If you already have such items, tweak them for more power. All the while you should pay close attention to the drivetrain as in most cases the rest of the drivetrain wasn't designed with the extra power in mind.

What's the deal with this "cone filter upgrade" I keep hearing about? Why would I want to do it and will it void my warranty? Will I get a lot of horsepower out of it?

The cone filter serves to increase the amount of air your car's engine can use for combustion. You will notice a power difference on both the normally aspirated and supercharged engines with this upgrade. The upgrade will void the warranty on the parts you remove (i.e. the stock airbox and intake plumbing) but if done correctly should not damage anything and should not void the warranty on anything else, although Pontiac could argue otherwise. The courts have ruled that unless the manufacturer supplies the parts free of charge, the owner is allowed to replace it with any part (from any company) made for that application. Make sure you know what you are doing before attempting this upgrade. If you desire increased power, this is a good and low-cost upgrade to perform. You won't get a whole lot of horsepower out of it, but you will at least feel a difference while driving.

I want to get larger size (either 17" or 18") wheels and tires on my car. How do I know which sizes of wheels and tires will be as close to the stock measurments as possible? Why not just get the largest size wheels and tires that will fit?

Here is a very limited tire size comparison:

The first line shows the stock configuration. The second line shows a close-fit combination for 17" wheels and tires. Other combinations will work, but will have a different percent error. Check other size comparisons at the Miata site.
Also, check out The Tirerack for a comprehensive selection of tires and wheels.

What's a "remote starter" and why would I want one? Can you help me install it?

A remote starter allows you to start your car's ignition without being physically inside the car and turning the key. It is controlled by a button on your keyfob. You might want one if you park your Grand Prix outside during cold or hot months so that you can start your car from inside the house and let it warm up or cool down before getting in.

Is it really true that if I get a new exhaust that I can gain 20 HP? How much will this cost me?

In general, no. Beware of false power gain statements made by any companies. A general rule-of-thumb for exhaust power says that for each pound of decrease in backpressure (pressure translated back to the engine by restrictions in your exhaust system), you gain approximately one horsepower. Read the backpressure study done by Thrasher Engineered Performance on a stock Regal GS (same powertrain and exhaust as a stock GTP) for more details. The bottom line: even if you dropped the whole exhaust system off of a GTP from the catalytic converter backwards, you'd only get a 14 to 17 HP increase. Realistically, you need mufflers and possibly a resonator or glasspack of some kind, bringing the real-world possible HP gains to less than 10.
Also, be aware of the possible damage to your engine that changing the backpressure can do.
As far as which kind of system to go with, this is wholly a matter of personal preference. If you're looking for a better sound and don't care about performance improvements, one type of muffler might be better for you than another. If you'd rather increase the performance and sound, you'd be more likely to replace not only the mufflers but also the resonator and complete piping from the catalytic converter to the tail pipes (hence the term cat-back system). At this time, Borla, RAT, and SLP are known to make a full bolt-on cat-back system for the Grand Prix. Many owners have opted for a custom solution (that is, they choose mufflers and tips and specify to the muffler shop how they want the pipe routed and sized). A Borla system can cost you around $599 or more, while a custom solution could be done for as little as $350 to $400 including labor.

Some other car owners have installed gauges in their cars to monitor information that wasn't provided in a stock gauge. Why did they do this, and should I do it? Where could I mount the gauges?

Many enthusiasts prefer to monitor important parameters, especially when they begin modifying their vehicles for more power. If you change your car's performance, you should probably maintain checks on certain parameters to make sure you don't do any damage (an example is transaxle temperature). Also, you may be curious as to how a certain parameter runs in your particular vehicle, such as "how much boost do I get at WOT or idle?" In this case, you'd install a boost gauge (the electronic boost gauge is not very accurate nor does it show values, just a percentage of full boost). A custom-made A-pillar gauge mount is available for your Grand Prix so you can mount two gauges of your choice within easy view on the A-pillar.

Can I replace my factory head unit while retaining the use of my steering wheel radio controls? Can I also retain the HUD display of radio information (if equipped)?

There are head units that, along with an adapter, allow you to retain the steering wheel radio controls. Sony is the only currently known manufacturer of such head units. The adapter is made by Soundgate and can be obtained through Crutchfield if necessary. Unfortunately, the HUD radio display can not be retained with any aftermarket head units.

You may purchase these items (and many more) through the