RE: tower hobbies tuned muffler?
I did a test on several .46 size engines and at the end, installed a Tower muffler on 3: OS .46AX, Magnum .52XLS & GMS .47. The prop used was a fun fly 12.25-3.75 and the nominal gain was 700-800 rpm compared to their stock mufflers. Other people have reported a greater gain on sport size props.