If you make the expansion chambers , I sure hope you photograph the process! I find that intriguing. I remember talking to a guy that specialized in Kawasaki triples and he had made numerous sets of expansion chambers. He said it wasn’t that hard to do ( for him anyways ) it always seemed like voodoo science to me , to figure out how to get the right amount of interior volume in a chamber. It has to provide just the right amount of back pressure.