It is agreed by anyone who has done this already that changing the SuperCharger pulley is the best bang for the buck.
On a stock GTP motor, you can safely run a 3.4" pulley with virtually no drawbacks, no SES lights, and little timing issues.
It is recommended that you install a transmission cooler with this modification because of the dramatic increase in HP and Torque.
Do not attempt to change a SC pulley with any other tool then the one designed for this application. You may destroy the SC snout.
To get the most out of the pulley swap, Cold Air Intake, and Exhaust work will help bring out the smaller pulley's full potential.
There are a few different ways you can go when changing the size of your SuperCharger pulley.
If you would like to keep it looking stock, and for the least expensive pulley swap, a press on pulley is for you. It looks very similar to the stock pulley, only it's a bit smaller. Helpful if you would like to convince anyone that you are running a stock motor. You will need the proper tool to do the swap. We can't emphasize how important it is NOT to use a puller that you can buy at your local auto store. Experience with the tool is also helpful. If swapping your SC pulley interests you, please ask around, you should be able to find someone with the tool, and experience to help you out. Here is a picture of a Pulley Boys puller.
Next option would be a "Quick change" pulley system. This requires the same tool to remove your stock pulley, and press on the "Hub" for whatever system you decide to go with. After the hub is installed, it's just a matter of using a common wrench to make a swap. Great for the track, if you are tuning and want to go between pulley's.
Here is a picture of a ZZP 8-rib quick change pulley on Max's car.
And a picture of Pulley Boys quick change on Thomas' car
Last popular system for swapping pulleys is to replace the stock snout with an aftermarket "keyed" snout. This snout uses a "keyed pulley" system which allows you to easily change pulleys on the go. To my knowledge, they don't have offer an abundance of different sized pulleys. This is the way to go if you ever need to replace your snout for some reason. Affordable compared to Mr Goodwrench.
