sbp expansion chamber?

Bluenose,
I have a PK80 slant. There was a world of difference in power with a pipe. A big difference without "Tuning" (adjusting the length) right out of the box. As far as noise, the SBP pipe is pretty quiet during normal operation, if ya crank on it and it "comes on the pipe" I don't think it's much louder than stock, noise is coming from behind you(in my case).
Hope that helped.
Mac

All you have to do to tune it is first have the motor running well BEFORE you put the pipe on, install pipe, warm it up with a short run, do a full throttle run for approx. 1/4 mile, hit kill switch @ full throttle, let cool, read plug.(this checks the Carb. rich/lean) adjust "C" clip as needed, repeat as needed, (sounds simple and quick, not always) if your close with the carb, you will feel a big difference, since your running a 49cc, they usually rev a bit higher, you may want to shorten, instructions come with the pipe or are on SBP web site.
The weight is just right, not to heavy but durable, I welded a bracket on mine with a MIG welder, no burn thru issues, just don't fall asleep while your welding on it or get a shop to do it.
Hope that helps
Mac

Fully assembled the pipe weighs just over 3 pounds.

If you want really quiet, slap the muffler on after the silencer.