I think it was covered early in this thread but I want to throw another vote in for removing the air silencer. Who needs a short-ram? This is noticeably louder, gives you the sound you want, and keeps your air filter in its plastic box- no heat-soaking!
I also removed the tube that runs under the battery to the front of the car. Might put this back, but the tube was small-diameter and I questioned just how much good it was doing.
The price is right, too- $0.
ZC 332, SR 41, 03 ZTS, 5 speed. Traded 1-17-11 with 117xxx miles