Mike, here are three possibilities, the engine is drilled and tapped, by me, for a Fox .74 muffler, what you see on the right is a Fox muffler front end with a J-Tec Snuffler inserted into it. The muffler on the engine is an MVVS .91 dustbin muffler and is fairly quiet considering that there are no guts in it. The war weary one laying on the left is a Davis SoundMaster that is very quiet, does not hinder rpm and makes great muffler pressure. By the way, that MVVS DustBin muffler will paint your plane with Diesel exhaust better than any other muffler, and yes that is an MDS carb that works flawlessly.