Then you want Fast Intentions. A tad pricey but totally worth it. It's the highest hp gaining exhaust available (that I know of) for our car right now, and it's top quality. It sounds amazing, not too loud, no rasp. This is the exhaust with carbon fiber mufflers and no resonators, so it's the loudest combination you can get for this exhast.
I would also go with handling first. Swift springs for $350 brand new are great, and Whiteline sway bars are also a great mod. The Stillen Gen3 cold air intake is about $525 new, but you can get them for $300-400 used here on the forum. The basic list of engine bolt ons is Cold Air Intake, Catback Exhaust, and Long Tube Headers/Cat converters, Pulleys, Intake Manifold. After that you're looking at forced induction which gets really pricey. For handling you want to look at drop springs, swaybars, wider wheels, and a big brake kit.