ok, so im looking at puting cutouts on the stock y-pipe after the cats, is the piping 2.5"?

 

i know that the pipe after the y pipe is 2 1/4..i would imagine the y pipe is the same size

 

its 2.75"

you need the cutout y pipe thing to have put in the exhaust.

 

You won't be happy with the sound of the dual cutouts open if you still have the cats. Won't have the "open header" sound. And when the dual cutouts are opened the tune needs to be changed if you're seeking max performace.

 

That really only applies if the rest of your exhaust is terrible. I did back to back runs on the dyno and saw a 2hp difference at most, at 6500rpm no less.

 

I'm just saying for "max" performance a tune is needed. If he doesn't have a good handheld programmer or tuning software already I wouldn't mess with the tune. Not worth $75-$200 to have some shop make a few tweaks. I'm use to 500+hp cars running 10s that want every single horsepower out of their setup.