MOPED ARMY

If you want more high end you can shorten the dwell center section of the pipe or shorten the header

Is there any difference in modifying either of those two sections? What kind of lengths are we talking, a couple inches, or more precise than that?

I made a estoril copy and ended up cutting 4 inches out of the header. The header I used was just a 1/16 of an inch less in diameter than the actual estoril. Cutting out some of the dwell should have a very similar effect but I have not done this yet. If you have a Boss pipe laying around you could add a dwell section to see how it hits lower. These are the easiest ways of altering a pipe w/o restrictions

I cut about 2 inches off the header, screams on top, but made the bottom and mids real boggy, and I have been playing with idle jets and needle setting to try to get more out of the bottom, but still no luck.

I agree with the theories Steve has shared. My experiments are with shortening the technigas. I would imagine the same variables would come into play of which of the stage pipes to cut and how much of each stage to cut for the desired effect you are looking for. I used 7 inches of header from the flange of a biturbo for an a55 and welded it onto a technigas cutting the second stage to a length of 5 inches. The results were outstanding. It's the only pipe I've made that makes an a55 50cc motor hit the rev limiter at 47 mph on the flats with an ST.