I don't get it, why don't these muffler makers make a tuned muffler for our gassers ??

it seams they make mufflers and then they make tuned pipes but nothing in-between,, I have found on my MVVS 35cc that just a difference of 2 or 3 hundred RPMs makes a noticeable difference in performance,,

I don't need a 26 inch long tuned pipe hanging off the side of my plane, but a different muffler that would give me a simple 300 RPM increase would make me very happy..

Jim