I have heard about the mythical backpressure theorys, and as far as I have tested, they are all crap. My experience in general, less backpressure = more power.

I have seen a few 'oddball' cases where seemingly positive exhaust changes produce unexpected results, but I am not 100% sure what is at work in those cases. They need more study to determine the real cause.

Having said that, I am open to hear about anyone elses real data on the subject.

Brian
EFI-Unlimited