asmund,

i agree on the muffler mounting, but i took FlyboyDave's advice and didn't use the muffler gasket, but instead, used RTV sealant and used loctite on the threads.........never loosened up.

as for not being able to make the engine quit by blocking the air, think about it, the engine is leaking air just as some of us have already discussed. yes it idles, and will idle super low, but have you flown the plane between just less than 1/2 throttle to 1/4 throttle?...........that's where mine (but not at first though) started to act up, and got worse as it was run.

also, you do know that AMA has a rule that says you are suppose to be able to shut the engine down by using your TX, whether pulling the trim down or using the shutdown button or switch?