Dart,

I don't know about how the muffler mounts. Not clear to me from the pictures and there are no specifications published that I've been able to find. At this point I would suggest a call or email to Keith at BME. In the end I think we will not know the final details of this engine until they ship. At this point I don't know if anyone understands when that might be. All I know is that there have been delays.