i know that the s4's use back pressure to open the 5th and 6th ports on n/a 7's so i was wondering since the a'pex N1 piping flares will the larger hole allow enough back pressure to open the other ports?

thanks chris

 

are u gona still use cats on your car ?then if yes you`ll be fine . i gutted my cats on my frist rx 7 86 and everything worked fine .

 

well it would be a cat back system anyway so it should be fine with the cat it comes with right?

chris

 

I dont think the cat is included in catback systems... catback refers to everything behind the cat.

 

oh ok thanks for the help