BOOHst - Our Pontiac Grand Prix GTP

BOOHst - 2002 Pontiac Grand Prix GTP

Back in the 80's I used enjoy surpising Buick GN's. But I liked the fact that they were relatively potent, generally reliable and somewhat comfy and efficient. I liked them so much I nearly bought one in 1989, but instead, we bought a Cavalier.

In 2003 we suddenly ran into some transporation problems. My wifes regular car (a van) was destroyed, along with our family. We were left with a 1990 Cavalier ("my car" with 245,000 miles and all ratted out) and our worn out 1990 Suburban.

I needed to get a reliable car, quickly for Laura to run around all over Georgia for rehab. A T-Type Regal would have been nice, but Laura specified the car had to be a 4 door, and have a warranty. So no regal. Honestly, we needed to focus on putting our family back together - not getting something I'd have to screw around with to make run.

As everyone knows I'm a chevy man. And the Impala, while a 4 door - didn't come with a blower. I had been eyeballing the GTP for a while, and hey... they come in a 4 door. If I got a relatively new car it would still be under warranty. This would be an easy sell... So I went shopping.

I found a possible candidate in Buford GA. I wasn't thrilled it was at a dealership but that's where it was. I figured out what I wanted to pay for the car and told the guy "no bullshit... here's what I'll pay". And the guy said "OK". I said "really? I'm talking total price". He factored the tax and other bullshit into the price and made the total price of the car what I was prepared to pay. This was at John Bailey Pontiac in Buford Georgia. I was happy with the sale.

One thing of interest - before I bought the car, I ran a carfax report and noticed the car had never been titled. It had 14000 miles and was being sold as a used car, but it didn't show who used it. When I went back to Bailey to pick the car up, I asked them what the story was. My car had been used as a Pontiac Executive car. I had a friend obtain the cars history at pontiac and found out it had 2 warranty issues - a wheel vibration at 300 miles, and then they replaced the wheel & tire at 1000 miles.

Technically this is Lauras car. I get to drive the cavalier every day (yee-haw) but occasionally I can get my hands on this thing. I also have to do "car maintenance" and I can't help but want to tinker with it. I have to be careful to keep the car reliable though. This car has ran excellent. I changed the oil on it a couple times and had to replace the tires. Other than that - we drive the car and it goes. It looks pretty spiffy too.
2009 Update: Laura got herself a 2009 HHR, so I got my hands on Booh now.

Named BOOHst - Boost is what a supercharger makes, and Casper the ghost (being white and not easy to see) likes to say BOOH! when he surprises people.

Engine: Supercharged 3.8L V6 - RPO L67. 245hp
I'm doing gradual and calculated tweeks. Since this is/was Lauras car, I can't break it. Nor can I do mods which would cause the car to become unreliable. This means most of the mods out there, especially if you don't think them out well (or do them right).

Update: I have a spare blower, so I'm rebuilding the snout on the spare with a modular pulley system. Pulleys I have are 3.6 and 3.5. Stock is 3.8. I'm putting an underdrive waterpump pulley on too.
View Supercharger:
Primary Blower | Blower removed (during intake job) | Snout rebuild goodies | Blower Rotors

My car had the intake leak issue, and laura noticed the car smoking or smelling occasionally. I noticed oil building up on the exhaust manifold. While fixing the intake leak, I also fixed the valve cover leak(s) (which ultimately turned into a recall issue). My car never went in for the recall since I repaired the car myself.
View Intake Gasket repair & 100K maintenance:
L67 Before | Intake Spoodge | Valve Cover skuzz (recall deal) | Intake Leak (blower removed) | L67 Fixed, along with 100K maintenance

Next engine mod will be high lift rockers. View stock rocker arms.

stock engine

Intake system - I put a fenderwell intake (FWI) on. It's generic and cheap. I got the cone through work. The first time I fired the car up after the switch laura caught me. She complained "what the hell is wrong with the car? It's loud". Oh... I fixed it, it's ok. Getting rid of that silencer really allows you to hear the mechanical WHOOSH and blower blades whiring. SWEET.

Exhaust - I got a 2.5" high flow downpipe with cat and removed the resonator. The assjet dyno confirms the improvement in low end torque. The car has a nice subtle burble to it. I'm going to add a stainless powerlog front exhaust manifold along with a ceramic coated crossover to try and improve flow and cut underhood temperatures.

view exhaust modifications:
Stock vs. ZZP Downpipe comparison | Stock exhaust system | ZZP DP w/Resonator | Modified Exhaust system (finished)

Programming - still being decided. I want to make sure I can scan my suburban and ultimately talk to the GTP (at least). LS1M & HPTuners are being considered. HPtuners won't work with my truck. LS1M can scan (both) to a PDA but I gotta make or get a cable for my PDA. HPtuners will scan both and talk to the GTP but doesn't appear to be optimized for the L67, nor can you use a PDA. Oy. I wound up getting LS1M for my PDA, and I have an Actron OBDII real-time scanner - so I can scan most of what I own. I'll probably need to get HPTuners or something like that.

4T65-HD. Stock. The 2.93 cogs ain't doing it for me. The car seems lazy on the low end, as expected. This is partly due to the weight of the car and the fact I don't put my foot into it. 3.69 gears are what this car really needs. I'll fix this later. Obviously this car cruises rather well and if you want to pass someone you just put your foot into it and you'll go by them. Having 4.10's in my other cars & trucks makes me spoiled.
If/when the trans comes unglued - I'll have 3.29's put in it. This seems to be the general consensus as to what's practical. I also have a shift kit for it.

Wheels & Tires: When I bought the car the base wheels were on it. I noticed the car was origonally equipped with optional wheels. The dealer must have allocated them elsewhere before I showed up. Not to worry, I kinda like these boring wheels. They add to the sleeper look. After burning up 3 sets of BF Goodrich Traction T/A's - I got a set of 225 60x16 Michelin Harmoney tires. These should be good for 80,000 miles.
stock wheels

Suspension: - It was stock for a long time. This car handles like a barge. I'd have thought that a "performance" car would be tight, but this thing handles like an average sedan. It may be because I have my tires inflated to the max pressure allowed to maximize fuel milage (currently 25.0MPG). But something didn't seem right handling-wise. (Maybe it was the stock FE1 "Soft Suspension" Option).

I obtained the GM Performance front & rear swaybars, and rear control arms. I'm putting the rear stuff on now. I'm not looking forward to dropping the front frame to slide the new front bar in. Plus the rear tends to be the area that shows most improvement when tweeked.

My struts have probably had it too. They only have 120,000 miles on them. Supposedly the AGR struts are the cars meow.

View rear suspension upgrade:
Rear Stock, (Removed) | GMPP Rear Control Arm | GMPP Rear Swaybar | Rear Suspension


interior interior

Amazingly, after 5 years of laura using the car for work and kids sitting inside... the interior is in very nice shape still. I have to replace a rear door panel cause someone picked a hole in it.

General Options:

Note: Interestingly, the car has a leather wrapped shift knob and overhead console. neither indicated specifically on the SPI list of RPO's. Car handled like crap probably due to the FE1 "soft suspension".

Driving Impressions: - Neither of us beat the piss out of the car so it holds up well. I'll occasionally excersize the car but I usually don't floor it. It's really not necessary. I had planned on bring the car to "work" once, and would be home late cause we were going to the track afterwards. I got an "OK...." then - "wait a minute... are you going to drive the car AT the track?". When I said, "er, yeah". I wound up taking the cavalier to work that day as usual. So no timeslips yet. I'll sneak a couple in.

Mods in progress (or planned):
The "GTP Supercharged" badges "fell off".
A set of drag radial baloneys (245 50x16?) up front would look pretty sporty.
I'm jonesing for a Daytona Pace car hood.
I need to get a spare (core) set of rocker arms.

Informative links & Info:
Club GP
ZZP Performance
W-Body Store
HP Tuners
misc mods
GTP World

Last updated: 2/5/2009
Author: MadMike Maciolek
Email: [email protected]

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