i am about to buy a top speed pro1 exhaust. I called the company and talked to the guy. He said if i the exhaust with 3inch piping that bolts to the y pipe i will get more power and a more aggressive tone. My other option was a 2.5 piping that came with a y pipe. Im not sure which exhaust will be better for my car and sound aggressive... any suggestions?

 

I'm assuming your N/A, in which case the 2.5" piping will be adequate as far as performance. The 3" piping will be louder.

 

I'm 99% sure I read Tony, when doing his R&D for his exhausts found 3" yielded lower power gains than 2.5" on a NA engine. Both will sound aggressive, but 2.5" piping will give you more usable power.

 

^I believe Tony was referring to the piping coming from the headers, which is why the MD 3" exhaust has 2.5" piping at the front of it. But it sounds like the OP has OEM cats and Y-pipe so the size of the cat-back shouldn't matter.

 

Some good info from Motordyne on piping diameter.

http://my350z.com/forum/intake-exhau...k-for-n-a.html

 

Our cars only need 2.50" pipe, anything larger will only hurt low RPM torque if we're discussing a true dual cat back system....y-pipe back it won't matter.
Gary

 

^+1