hey i just bought a 2001 Grand Prix GTP and i'm looking for some upgrades, i've been told to remove the u-bend and the resignator and replace them with a strait pipe. i want to know if this is leagle. i've also been told that putting a smaller pulley on the super charger can add a good amount of hp. i am open to any sugestions for upgrades, so whatever u got let me know. thx.
Removing the u-bend and resonator is perfectly legal. I used to work for a
guy that started making u-bend replacements before anybody knew what they
were. I used to specialize in Grand Prix's. If you get a set of headers,
a 3" exhaust w/high flow cat going to dual 2.5" mufflers, you'll pick up
gobs of power. Doing the exhaust will most likely gain you more power than
using a different supercharger pulley. A supercharger pulley would
probably only gain you 20hp or so. I'd also recommend a cold air intake.
With a cold air intake and the afore-mentioned exhaust mods you might
notice a drop in peak boost pressure. The reason for this is because by
improving airflow in and out of the engine you are increasing the
volumetric efficiency...meaning that the engine is able "breathe" easier
and fill the cylinders with more air/fuel.
If you performed those mods, and did the pulley, you'd be running pretty quick and I'd recommend at that point to upgrade your fuel injectors. There is also an electronic shift improver available for you car that is completely adjustable to driver preference...and the great this is that it only takes a few minutes to install...it just plugs into the trans harness. I'm probably leaving things out but this post is long enough as it is...if you have any more questions, feel free to send me a private message.
I don't know if the 01 GTP has the same tranny as the newer ones but we have a lot of folks come in with screwed up trannies after they do a few mods on the engine (mostly just exhaust/intake/supercharger pulley)...so, watch out for that (heard the tranny is a little weak-ended).
I haven't seen any problems with the previous generation 4T60E or 4T65E transmissions in cars from that year...half the problem is people try to be hard-asses and neutral bomb it to do burnouts and end up doing transmission damage. I came across a guy running 12's in a brand new GTP and it looks stock from the outside!
We had one guy come in with a bunch of bent valves after he did a Supercharger pulley swap and exhaust :ohcrap: . Turns out he did install it right, the engine was just a lemon.
GTPs are fun cars to mod.
^^^ that's the guy that I was referring to as having a 12 sec GTP that looked stock externally. Thats a pretty piss-poor '60 ft time, but I guess you can't expect too much from a fwd vehicle...It seems as though you have plenty of power to pick up the slack down the rest of the strip though.
thx for all the help guys i think i'm gonna go with an intake and exhaust first off, and then maybe later change the pulleys and injectors. i'm thinkin bout going with slp headers and i'm not 100% sure on what type of muffler i should use so any suggestions r apprechiated. and i'm gonna go k&n for the intake unless persuaded other wise so thx and i'm still open for more suggestions.
Alot of GTP guys go with the Magnaflow mufflers. A 7-9" cone filter should
be fine. Good luck!
I am racing again this friday, hopefully I can get my "pisspoor" 60' down to a 1.9 and get a 12.5-12.6@108
I am using new drag radials and alittle more boost!
I have a 3" exhaust which splits to a dual 2.5", with headers/no cat/no resonator but I still have the stock exhaust tips, LOL!
Good luck on picking up on your 60-ft times...if you could get down to less
than 2.0 and you'd be flying high. Keep me posted. :smoke:
Also, a lot of GTP guys I've seen are using a cold air intake that runs through the inner fender-well and picks up the air behind the driver-side fog light...can't remember the brand, but I've heard nothing buy great things about it.
Hey gtpsleeper how much did you pay for your 3" exhaust and where di you get it?