Little change in exhaust sound (if you use the stock exhaust). I had the hi-flow cat. on my RB exhaust car & I would say it was about 10%-20% louder.

The hi-flow cat will give you better gains. Not only proven by RB (who I trust implicitly), but when I dynoed my hi-flow cat I got 5 whp (179 to184). The exhaust gave me about 2.5-3 whp (176.5 to 179).

 

Alright, so far scratch the REVi, CAI, midpipe and the pullies. That effectively saves me around $1200 that I intended on using. I guess this can go towards my SC . BTW, does anyone know how much the Hymee exhaust weighs? Is it lighter than stock? And how well will it work with FI applications. I remember reading somewhere that the RB exhaust wasn't made with FI in mind. But don't qoute me on that, I've been in the desert for a while so my memory is shot :o . Any other suggestions on what direction I should take would be appreciated. I'm actually learning a lot, thx guys.