How to Modify Your Pipe for more Torque
Just cut the baffle and weld in an extender as this daigram shows. That reduces and elongates the return baffle wave. That wave, at low and mid-range rpm, only fights against the return diffuser wave which results in less delivery ratio (ie: less power). It only is of service at top rpm when it serves to increase delivery ratio and compression.
The following picture is an example of what I propose on this page. The owner added in a baffle extension, connected a stinger to the side of the extension, and then welded shut the end of the pipe. The baffle extension is 5" inches long. Here´s what the owner said: "I bought one of the banana expansion chambers for my Bikeberry 66cc and was not satisfied at all. So I took the saw to it... I read your stuff on the torque pipe, sort of combined the two. I like how it came out ( I´m 100% function over form). Header length from piston to weld where first cone begins is aprox. 13 inches [the banana pipe comes with a 1" header pipe]. Well with the original banana expansion (the one I cut in two to make what u see) it had way better acceleration over stock but topped out at 17 mph. Stock was 26 mph per IPhone bicycle gps app. After the pipe u see in the pics acceleration better than stock but less than the untouched banana pipe. After playing with jetting ( #73/.023") I get 27 mph but way smoother. Also about as quiet as the original hotdog pipe." If the owner wants it to go faster then he can shorten the header. If he wants quicker acceleration then he can shorten the baffle extension.
Here are the calculated return waves for the normal and the modified baffle section: