ORIGINAL: Sport_Pilot
Just fill one of the exhaust tubes with JB weld, or crimp both of them. But if the engine is mounted sideways and you have even a little muffler pressure you should be able to tune the engine.
No it doesn't work.
Plugging the tubes does nothing with this engine, neither does crimping them.
The Pitts muffler is to blame. The TH needs some pressure.
The stock low pressure output muffler, will do even when the engine is inverted. The Pitts kills the engine every time no matter what you do.