The worst thing I did was put Altezza tails on my car in HS. They didn't last long, as I took them off about five or so months later.
Not that it was bad, a few compliments from some of the girls in class.
I just wised up and said Altezza's were ricer.
After that, I didn't do much - got an SRT4, put Stage 2 on it (injectors, WGA, and PCM) and full 3" turbo-back catless, non-resonated exhaust (sounded beastly, but freeway drone sucked) on it and tracked it at the local strips. Nothing ricer-ish about it - I even took the stupid wing off of it (OEM) a month into ownership.