Well, the backpressure thing is a myth. What you are looking for is correct flow speed.that wouldnt work very well would it. Wouldnt sound good either. Doesnt a mufflewr create back pressure in a cat back system, w/o it it wouldnt run properly correct? if im wrong feel free to correct me, wouldnt be the first wont be the last.
I assumed he was talking street car. As I would guess the majority here drive on the streets. I personally have raced on REAL tracks and have been doing so since my first race at Fontana in 1966 in my 57 Chevy. I race motorcycles too.