Originally posted by /^Blackmagik^\
it is a myth that any engine needs backpressure to run. if this were the case we would all be sporting .5" exhaust piping, not shelling out the dough for a performance cat-back exhause or whatever. the reason too big of a diameter exhaust piping will cause loss of horsepower is not because of lack of backpressure, but the extra surface area of the piping causes the exhaust gasses to cool. this slows the exhaust gas velocity and causes backpressure.
are you 100% sure of this? Because i swear, MOST people would say otherwise.
Where did you "learn" of this explanation?
Dave