^ You don't need all that to run a 3.25. You will NEED flow mods to run it safely though.
Headers or a PLOG/downpipe combo (headers are better)
Cam or rockers would be the next best thing to improve flow. Check around for which you'd rather do (cam will have more affect on the car and more possible power output, but rockers are easier to install)
And/or a fullsize intercooler. Skip the short stack IC, no reason not to go fullsize. This is one of the best ways to combat knock and to drop pulley sizes.
E85 is a great fuel to use to get more power, and to kill knock. Depends if you have easy access to E85, but will require larger injectors and a fuel pump upgrade/rewire
A tune. To be running anything smaller than a 3.8 pulley you really should get a tune. Mail order tunes are okay as a baseline, but getting an in-car tune is the way to go.
If I were to take a stock GTP and make it run a 3.25 pulley I would get/do:
Speed Daddy headers
Ported Gen III
Cam-your personal choice w/ supporting mods (valve springs, retainers, timing chain/dampener, etc)
60# injectors (while not needed, it will allow for more headroom with tuning and further upgradeability)
Open cone intake
Custom tune.
