I have an exhaust that was originally installed on a CT Baja 50 four stroke (hear me out
). The Yamaha PW80 was so faithfully copied, that the manufacturer stuck an expansion pipe on the four stroke engine. You can imagine how long I left that on there.
The only other spare two-stroke pipe I have is from an old YB100, and it doesn't really have an expansion chamber.
The PW80 style chamber is yours if you want it.