Originally Posted by 1QuikWS6
Be careful removing all the restrictions and opening up exhaust size (greatly reducing factory built-in backpressure) - on the NA cars it actually has a detrimental effect and you LOSE low end power.
Cars were designed to run in optimum condition with a certain amount of backpressure.
Do a Search on here and do some reading 1st...
I read about backpressure on the forums last week, I can't remember which one but it's not backpressure that we're losing. The guy made sense that it is the exhaust velocity being too slow. That's why we feel it being slow or laggy. He went on to go about it and I really thought in backpressure too until I read that last week. So now I think it's slow exhaust velocity.
OP I'm running on a 3inch midpipe from headers, no res, no 2nd cat with eisenmann race muffler, and x and h-pipe are for 335. 325, 28, 30i's use Y. BUT someone did say x pipe to reduce rasp. Just never been done yet or shown here.