x2 On what kato said.

Find out if it's a catback exhaust or a turbo back. If its only a catback, get a butler dump pipe. Most gains from an exhaust are in the dump pipe - and it won't it any louder or quiter.

Gauges are good if your doing track work / wank factor, but aren't absolutly neccesary for a general street car.

__________________
Twin scroll Pig Bi-Squeeling