[WADS56]

"IMO, the 2 1/2 would be fine for street driving, but at the track I would remove the cat back after a few passes and see what kind of difference it makes... Probably pick up some e.t./mph, only one way to find out. "
Thats why I wanted to get the 3" system best of both worlds.

"IMO keep in mind... they could also run 2 1/2 out of your ultraflos up over the axle and then weld on some 3'' extensions, another option. "
That would look cool, but the reason I wanted 3" was for the performance.

"Has the law been bothering you or something? Or do you simply want your ride to be quieter?"
I am converting the car back over to a street car (kind of) and turndowns with no sound deadning is killer on the ears.

"Rule of thumb -- smaller pipes make more noise (high pitch) than bigger pipes do (low pitch, deep tone). That is what I have realized working in a muffler shop. "
Thats cool... I like a car that screams not rumble.

Thanks for the help. Do you know what a mac flowpath muffler flows? The ultraflo's are like 1300cfm. So I was thinking that the 2 1/2 ultraflow catback will be better then the 3" mac catback.