2007 Grand prix gt supercharger pulleys

I was told by a guy working for 3800performance.com that the smallest pulley I can run safely on my stock 07 GT is a 3.5, 3.8 being stock. The smallest the stock super charger will accept is like 2.9. I was wondering what would I need to do to be able to run a pulley under 3.5. Maybe just a chip, cold air intake and changing the timing and maybe a higher octane gas or will i need to get into engine work?

well, as of right now there isn't a pcm or a tuner for the '06+ GPs, so you guys are limited in what you can do right now...

on the '04s and '05s, here is pretty much the guideline(will vary car to car):

180 degree t-stat
Cold air intake
colder plugs(autolite 104s seem to be a popular choice)
3" downpipe
tuner or reflashed PCM
Ported Exhaust Manifolds(or headers, depending on how far you want to take the car)
should be able to run a 3.5" pulley then...
I would also advise adding some higher ratio roller rockers, 1.9s are very popular, ZZP offers 1.9 modified stockers which don't need a valve spring change, but if you run a true set of 1.9 roller rockers like i have 90# LS6 Valve Springs or even 105# valve springs are recommended...


to safely run a 3.4" you will need headers or an intercooler...


with both you MAY be able to run a 3.3 or a 3.25

with the mods I mentioned(basic bolt-ons and a tune) + headers + I/C + a cam + race fuel a 3.0 should be safe to run(3.1 on regular pump gas, possibly a 3.25)...

for a 3.0 or below, you will need a lot of tuning specific to your car... I believe to run lower than a 2.8 you need a machined snout, I really don't know once it gets below a 3.0...

all of this depends on the car


the thing to remember is that the Gen V M90 produces a lot more boost and is a lot more efficient than the Gen III M90, so you can't go by the mods those guys can do to run said pulley, you have to knock our pulleys up at least one size, most of the time two sizes... For example, the mods that you could run a 3.4" pulley on a L67 is pretty much equivalent to what you have to have on a L32 to be able to run a 3.6" pulley, a few of us have had luck and are able to run a 3.5", I was one of the lucky ones... As far as how you know what you can run, if you are going to mod your car, I highly advise you have a scanner or have a way of easily getting one when you need to scan... LS1M and Autotap are popular choices, well the LS1M was, they are now no longer being made but you can find them used often on popular grand prix sites... Once you have a scanner(or can borrow one) you want to run a diagnostic on your car by running a WOT test, you will be able to view all kinds of variables, from boost, to ignition timing, to Knock Retard... Knock Retard is the name of the game, it is pretty much what hampers you from being able to do certain mods, you want to eliminate it before you even think about swapping pulleys... the basic bolts ons like a CAI, 3" downpipe, catback, etc. help fight it... Once its low enough you can swap pulleys, then scan again, if the scans are good, the pulley can stay, if not, you need to take it off and invest in more supporting mods or learn to tune with a tuner.. One common mistake is people think the smaller the pulley they run, the more boost they are running, the faster they go....

WRONG... when you add boost you can't, you create knock, which retards your timing, thus taking AWAY power and actually lowers your boost... So in reality, a car running a smaller pulley w/o supporting mods will be NO faster than a stock gtp but will be throwing a piston in a month or so, and its why with my setup I have beaten GTPs running 3.1" pulleys, because its not about the size of the pulley, its about having the mods to support the pulley you are running...