RE: header lenth
I just picked up a new pipe (need for speed) that has a header adjustment like yours. I am not sure I like the overlap of the header tube going into the pipe. I think I am going cut the tube 1/4" at a time, and test each cut, to get the tuned length that works best for the set up I am running. I* will probably buy a second header tube, in case my final cut went a bit to far. I am not sure, but I suspect the tube sticking into the pipe might effect the return wave duration or strength, and will most likely effect gas flow, so I want the header section cut off just past the last o-ring.