The 3mm TOC-53 has an excellent muffler, sound level is reasonable and they are well built, TIG welded and polished. And here's another not-so-obvious attribute. The TOC's exhaust port angles away from the spark plug about 1/2" which, on an inverted engine places the muffler about 1/2" higher in the cowl. This, plus the fact that the lower front corner of the muffler is angled, means that I have not yet seen a plane where the stock TOC muffler won't fit completely inside the cowl. This is pretty important, it's really disappointing to have to hack up your cowl just because the cheapie muffler won't fit.

For that matter the TOC-53 is, IMHO, the best of the lot, particularly now that I have the hop up kit which puts its power square in line with a DL-50. I did some side by side testing with Pianori's MT-57 and the TOC-53+ out-pulled his engine by a couple hundred RPM. Allowing for the improvement from fixing the timing (why isn't it right in the first place, how hard is that to do?) the TOC-53 and MT-57 are just about equal. With mufflers attached the weight is equal also.

And the TOC-53 definitely was smoother, owing to its 3 bearing crank that has counterweights ahead of and behind the rod. I have sold many of these engines and I know the service history, there is none better.

TF