I have the Stillen HF Intake on my 02'. What is the best exhaust setup/brand names? And Should I start with the y-pipe and work my way back? A few say that a cat-back may not be necessary. I have noticed several exhaust systems offered. I have only seen one y-pipe and one hi-flow cat. What is with the 15hp increase claim on the hiflow cat anyway?

While I like the sound of good exhaust, I don't want to wake my nieghbors every morning!

Suggestions from those who have been there????