If it were mine and I had the money to blow. Considering you posted this in here instead of a forum like wheels/tires/asthetic/etc, I am assuming you want it to be a little quicker.
I would look for an SVT exhaust system and slap that under the car. An intake would be a good idea as well. I know that D Davis is going to have one out real soon. There are also a few other suppliers whose names I forget right now. Faster you could go with a underdrive pulley (they have them pretty cheap on Ebay), perhaps even an intake cam. After all those are done, get yourself a chip and have them burn it so it will make use of all your new parts!
If you have some money left over (you probably will) you could have Chris Hightower paint your headlamps, lower it a little and throw on a nice set of wheels and tires.
Just my .02¢
