I heard from a local shop that a stock exhaust manifold flow really well like shorty headers from the factory. The question is:
Will stock exhaust manifold plus a cat eliminator and a true 3" exhaust back to stock mufflers will flow almost as well as long tube headers and a catback system for a car putting out 630 to the wheels?
Has anyone ever done any comparative testing to show the differance?
I know longtube headers and an open exhaust will flow better at high RPM's but for low to mid range RPM and general street driving, is ther really a differance warranting the cost?