3" y-pipe to 2.5" cat back
If you want to get more performance out of your existing system then slap a cutout on your y-pipe to divert the flow before the flowmaster....I saw a 15rwhp gain with a cutout when I had a flowmaster catback, and that was with stock heads and 1 3/4" headers.....I'm sure you'll see even more gains with a better catback since you have heads/cam and 1 7/8" headers
we carry flowtech cutouts in stock if you need a cutout to better accommadate the mods that you already have on your car
we also carry our TSP Rumbler catback system without tips in stock so you can use the tips that you already have...the system is only $175+shipping and its one of the better sounding catbacks on the market and for a price thats hard to beat
do a search on customers who have the system to see how they comment on the sound...etc or go to http://www.ls1sounds.com/tsp_rumbler.htm to hear what the system sounds like
Theres horsepower waiting to be utilized with the setup that you have!!
-Zach


