Re: Herky jerky slow speed cruising?
Back pressure is created by a restriction in the exhaust stream. At low RPM it helps a 2 stroke by keeping the fresh charge from blowing out the exhaust port.
At high RPM it causes the exhaust gas to remain in the cylinder. So it helps the low speed performance at the expense of high speed performance.
I have added a second muffler to a lot of my bikes and I can tell you that it does work. The motors all made less noise, idled smoother and would run smoother at low speed.
The only thing in my garage with 4 wheels is the lawnmower