Originally Posted by A_PHOBIA
there is ill effect...."you need a certine amount of backpressure"
Haha, nice try. The trick to a "perfect" exhaust system is to maximize exhaust velocity and minimize backpressure. A cat converter (I don't care how "high flow" it is) decreases exhaust velocity and increases backpressure, both cause a decrease in performance.
The same can be said about mufflers, but obviously you should leave a muffler on a street car.