Hello. Several local flyers and myself are using this engine for certain projects and we have all ran into the same problem. We need to use aftermarket mufflers and have gone broke trying to find one that works with this engine. We have bought Bisson , Slimline and JTec. Nothing works but the orginal!!!! The engine runs like crap on all other mufflers. We have tried a lot of things and have found the engine will run great IF we run a pump of some sort along with the other mufflers. What is the deal with this OS engine??? It should work ANY muffler.

Ken