98 Grand Prix GTP ?'s- Please Help!!

**Liquifire** · 06-16-2009, 06:36 AM

I just bought a 98 Grand Prix which had its exhaust hacked off and replaced and I had some questions. Other than the supercharged engine, what other differences are there between the standard GT coupe and the GTP version?
Are the stock exhaust systems the same between the two? Does anyone have pics of what the stock exhaust should look like under the GTP? Did these cars come with auto-dimming rearview mirrors or just a plain old school mirror with nothing on it? Does anyone have any pictures of what the dual climate control should look like?(mine has a unit in it that is not red in color for the backlighting, it is bluish(maybe out of a monte was my guess) Please help with any specs, hints, info, recommendations, etc. Thanks for any help.........Much appreciated. Anyone know of good pricing for equipment for these cars??? right now someone removed the stock exhaust, put on large truck style tips(looks ok from the outside though) but has also put in a glass pack behind the cat and straight pipe after that......it sounds straight rice to me. I wanted to put the stock mufflers back on but maybe with different tips on it to enhance the looks.

Thanks..........

**GTP231** · 06-16-2009, 06:54 AM

The exhaust systems are the same between the two cars. I beleive auto dimming was an option but I've never seen one without one.

**Liquifire** · 06-16-2009, 07:10 AM

It seems like a pretty loaded car otherwise.....It has HUD, moonroof, leather, dual climate control, CD changer(although no magazine in it, I believe it is 12 disc) no keyless entry-remotes lost? Although the car has 100K on it....it seems to run and drive well. Does anyone have one with aftermarket exhaust? Is there a noticeable gain and/or loss in HP or in gas mileage vs. stock??

**GTP231** · 06-16-2009, 07:17 AM

Cat backs aren't really worth much onther than sound until you're well into the 11s over stock. I'd get a front pipe with a high flow cat or without depending on your emissions concerns. There's more gains to be had replacing that than the cat back. They all have keyless entry so yeah the fob were either lost or damaged. 100K I'd give it a tune up and check the trans fluid condition. Mine has over 107K on it and still gets 30m.p.g. on the highway and runs 13.4s @ 103+ just fine for not a lot of money in it

**02Sweet** · 06-16-2009, 07:27 AM

I can't tell you what just a cat back does but a good friend of mine put the following on ALL AT THE SAME TIME at 125k

intake
larger down pipe
high flow cat
cat back system

The car pulls harder than ever compared to before when it was bone stock, he is getting the same mileage and wish he would have done all that stuff before

**Liquifire** · 06-16-2009, 07:41 AM

Originally Posted by GTP231

Cat backs aren't really worth much onther than sound until you're well into the 11s over stock. I'd get a front pipe with a high flow cat or without depending on your emissions concerns. There's more gains to be had replacing that than the cat back. They all have keyless entry so yeah the fob were either lost or damaged. 100K I'd give it a tune up and check the trans fluid condition. Mine has over 107K on it and still gets 30m.p.g. on the highway and runs 13.4s @ 103+ just fine for not a lot of money in it

not sure how fast it is......it seems to pull pretty hard out of the hole. I got 27 MPG on the freeway going 70-75. I don't want to hurt performance, just want to quiet it down a little. It shouldn't hurt MPG or HP much by going back to stock mufflers.........I think the easiest HP gains would be from changing the pulley on the SC........What PSI boost is stock for this car?

**02Sweet** · 06-16-2009, 07:45 AM

Originally Posted by Liquifire

not sure how fast it is......it seems to pull pretty hard out of the hole. I got 27 MPG on the freeway going 70-75. I don't want to hurt performance, just want to quiet it down a little. It shouldn't hurt MPG or HP much by going back to stock mufflers.........I think the easiest HP gains would be from changing the pulley on the SC........What PSI boost is stock for this car?

I can tell you that my buddy has the slp catback and it is a little louder than he wanted but he isn't going to change it now

**Liquifire** · 06-16-2009, 08:00 AM

Dont get me wrong........I love a nice sounding deep V8, but with only a 6 cylinder, it just sounds like rice to me right now.........

**GTP231** · 06-16-2009, 08:00 AM

Originally Posted by Liquifire

not sure how fast it is......it seems to pull pretty hard out of the hole. I got 27 MPG on the freeway going 70-75. I don't want to hurt performance, just want to quiet it down a little. It shouldn't hurt MPG or HP much by going back to stock mufflers.........I think the easiest HP gains would be from changing the pulley on the SC........What PSI boost is stock for this car?

I doubt going back to a stock cat back will hurt performance any. Stock is about 8 pounds.

**Liquifire** · 06-16-2009, 09:33 AM

does anyone have any pics of aftermarket hoods for these or cooler looking ground fx kits...anything. Luckily these have the five spoke polished rims, and those are good enough for me.

**ChrisJ** · 06-16-2009, 11:40 AM

www.wbodystore.com

www.pfyc.com

www.zzperformance.com

I have an 02 GTP just a lurker over here.

**Liquifire** · 06-16-2009, 01:25 PM

i assume that the supercharger has its own oil? how often should this be changed?

**cammed goat** · 06-16-2009, 04:57 PM

That F1 bodykit is killer.

**ls1camino** · 06-16-2009, 06:08 PM

I like the stock exhaust on mine...I like to be able to hear the SC whine over the exhaust.

I DO have headers, 3" Downpipe, and 3.4" Pulley...been beating down Mustang GTs left and right since I bought her 2 weeks ago

**cammed goat** · 06-16-2009, 06:18 PM

Originally Posted by ls1camino

I like the stock exhaust on mine...I like to be able to hear the SC whine over the exhaust.

I DO have headers, 3" Downpipe, and 3.4" Pulley...been beating down Mustang GTs left and right since I bought her 2 weeks ago

How's the plate idea goin?

**ls1camino** · 06-16-2009, 06:20 PM

Originally Posted by cammed goat

How's the plate idea goin?

I went with PSIENVY...thanks to whoever suggested it

**NJ 666** · 06-16-2009, 07:21 PM

My wife's has almost 180k on it and got over 30mpg on a recent trip. So far only a couple window regulators and typical high mileage stuff. I recently put the Eibach Pro-Kit on it and it was a huge improvement.

**Liquifire** · 06-16-2009, 08:02 PM

is the windshield washer dispenser motor located in the windshield washer fluid tank on these?

**02transamce** · 06-17-2009, 01:06 AM

you could also try www.3800performance.com

**0rion** · 06-17-2009, 07:18 AM

it's a damn shame GM didn't continue to make these cars. I miss the hell out of our old one. Didn't care much for the body style change though in 03ish 04ish or whenever it was they changed the body style. Front ends of the newer ones is ugly as sin.