Unfortunately it's not the same. Cutting & welding will have to be done before it will work. It will make a small change in the pipe "timing", cause pipes are made to a specific length for them to run in the rpm range you're shooting for. I don't know how significant this would be on a moped, but if you lengthen the pipe, to make it work, it will have maybe slightly more bottom end. Shorter pipes are usually for more top end. There are also many other factors. That's why it's called the "black art". I only know of one pipe that is currently being made for a Hobbit. It's the Motomatic pipe. They are completely made by hand & tho a little spendy, I can attest to the difficulties of hand made & therefore worth the money. I'd have to get at least that much if I were building something as complex as an expanson chamber. That may not be be answer you were looking for, but you would have no complaints with it either.