I've heated one of the all metal versions before tghey went to CF bodies. Heated it up, awful stinck from the glue, and removed the baffle. Glued it back together with hi tekp epoxy.

Yes it was new . Run on a test stand with the all metal muffler on ,now that you mention it probably not the best way you run a new engine. I also used nitro fuel in it . Now I hear that they don't like nitro unless you put in a few head shims. Chulan told me to run it for about one hour and it would be OK . I did not run it again . It still feels tight as can be . Hopefully it didn't get damage it . It has tons of compression .  I used 22% oil Sig 10% nitro .The same I use in my OS 40 . 20% Castor 2% klots . It was a one of engine black head plane bearing 46 he sold as a special on his web site many moons ago. I used an 11x6 ew rev-up

 He had said 18% all synthetic and that I felt would ruin it. It ran strong and 2-4 awesome . I was afraid to run it too rich as I had read that's bad for it too ! . So I pinched it back and forth from rich to lean for a few minutes and she was cooking hot . Not discolored or glowing red or anything like that just hotter that I am used to feeling an engine get on a short run like that .   Like I said very low noise level . I called Chulan after running it just that once and talked to him about it. He didn't think there would be a problem to just run it some more but I haven't .

 I am thinking a few head shims and no muffler would be best for the next run. But thinking that that muffler will never work out the way it is. So I was thinking about gutting the muffler . Anybody use it stock muffler with out cooking their engine ?