most everyone will say little bolt ons like a shifter and gears and stuff, but i go right for the engine, I got my 7up car about 3 months ago and in 2 days it will almost have a full h/c/i, lacking are the heads, but I would do a nice 373 gear and some underdrive pullies, then go find a mass air sensor out of a 94-95 gt mustang and swap it in it is a 70mm piece instead of the stock 55, you can actualy feel it gain with those mods, next go buy some nice headers, and some mufflers, pull the cats for now, but keep them because of inspection, and then go buy an off road piece that has no cats, and it will keep goin faster, then do a nice heads, cam, and intake package, and youll be good for high 12's!!