Well you can always get some sort of cat-back exhaust too, but usually most people tell me that it's just for sound. Oh, one more thing is the UpPipe, supposedly it's safer to get a catless UpPipe, but theres no power gain from it.
Oh, and I never said Invidia was the best
i just like it the best, price wise and everything.
edit- If you're going to be racing on the tracks, you might want to (as mosc stated) get upgraded tires. I personally love Falken tires. I have Falken's on my Jetta, and my buddy has Falkens on his tC. They work very well. You can always get BF Goodrich KDW g-force, or bridgestone, or whatever, I just have had (finally I have had personal experince with something
) with Falkens and I love them! Even my all-season ZE-912 tires are pretty damn sticky! My friend's tC has the Azenis RT-615s, which are track tires, which i would recommend for track racing, and also street use, they are a nice all-around tire.