Just to try and help out with some new info....

I took my stock muffler, a hair over 8 oz. Slit it in half at the bent over flange, and seperated all the internals out..lots of junk in there..I cleaned everything and jb welded the two outer can halves back together , with the two standoffs, or tubes that keep the seal tight at the ehaust once installed..I didn't skimp on the jb weld..and I came out at just UNDER four ounces on stock muffler...man the original thing was heavy! Now I am no expert on whether the jb weld will hold, or what the rpm change will be. But I thought someone might be interested.. Unfortunately I am not sure when I will get this motor on a stand and propped..so I can't guarantee any running info in the near future..

hope this gets the ideas started though, anxious to hear some flight reports ..mine MIGHT be going on a 62 inch 3d profile...