From my calculations, I dropped 70, was 250, now 180. Got three flights yesterday without issue, so for now it seems fixed.

It seems like a big reduction, so I'm not really sure that the the t'couple was making adequate contact with the head. If if I feel motivated I'll try this again with it better attached.

Yeah, this was with the bisson muffler, which to be honest I don't really like because its REALLY LOUD.

I flew the plane yesterday with a 14-4 and the guys were asking me if the muffler fell off... it was quite unbelievable. Someday I'll get something quiter but not now. Its much quieter with the 13-5, and also about 500 less RPM.

The power is still pretty poor, before the first overheat issue it seemed much better, but it could be my imagination.

Also, it now hesitates when throttling up, and idles much poorer than before the overheat issue, but since I changed the ring, I probably didn't align the cyclinder properly but I did the best I could (if its off,,, I can't tell by looking)

At least its now flyable. I think I'll upgrade next year to either an OS75 or the ST 90.