I bought a Sears 22 HP Kohler mower (w/0 50" deck) from a neighbor, as I had another older one starting to fail. The guy that had cut the muffler off and added a 3" vertical stack. Sounded like a Harley MC, and very loud (required ear muffs). My old one just siezed up in the transaxel so put that muffler on the Harley Mower and now I have one I can use w/o ear protection. I have a ne Husky mower so use it for a tower. He had it that way for several years and did not seem to have any adverse effect. Time will tell.
Ron