The popular bolt-ons are(listed in no particular order):
Gears (4.10 minimum, 4.30 or 4.56 are probably more favorable if you race more often at the drag strip), shifter, drag radials, exhaust (midpipe/catback at the very least, add headers if you have extra $ and don't mind the difficulty of installing them), cold-air-intake, etc, etc...pretty similar to your mod list for your '03 GT listed in your signature.
BTW - Whatever you do, don't use MAC longtubes on a 4V engine...