i have mac headers, an mac offroad h pipe and mac catback, but put turndowns on and took the tips off and sound good at idle but not real fond of it at mid rpms and it sounds good at full throttle. My exhaust performs good , with 325rwhp all motor so, take it for what its worth

 

That is the same setup I just picked up but I got the h-pipe with high flow cats. I have yet to install it though. What else do you have done to the car? Pulleys? TB? Intake manifold?