they only get the best kind LOL well the book i have which is the topic being discussed talks about diffrent shaped chambers and lenght for diffrent engine speeds at no point dose it say you can have a chamgber that dose it all, the chap who wrote the book said he had several chambers when he went racing some for wet conditions some for long circuits which need top end, and twisty tracks where you need more mid range, I guess the stuff we buy for our bikes is a happy medium. but make your own, no thanks ill get mine from Paul or Matt