is there a hp diffrence with tailpipes vs. turndowns

[84LX89GT]

Ron1, you are correct, i was talking about resonant tuning. What i was basically saying was i've heard of people using backpressure as well as all the other things i talked about (diameters, lengths, etc.) to tune the torque band of a particular engine to it's intended use, and some engines don't benefit from zero backpressure....basically what you just said
This was a good discussion, i'm always up for learning something new.