RE: 4 stoke without muffler
OK...I love my Magnum 91 but it seems to just not do it for you.... and that is fine.....You have done verything to add more power....
I really think that your only option is a larger engine.....
removing the muffler will make your engine noisier and messier......IMHO......
I think ti is time to just suck it up and buy a larger engine.....
just my .02