I have replaced my OS 91 FSa with the new revolver in my 2nd Revolver. Wow verrrry nice! A nice sized egine which is very quiet. A couple of comments: 1. Do no like the oil exit port tubing location which interferes with my engive mount a bit . 2. My idle arm became loose during break-in and cause much grief until resolved. 3. New mffler very quiet but alas it is two piece which may mean a constant revenue stream for Tower (does inclued a rubber gasket) 4. Fits 91 mounting holes and does offer nice power package.

Overall a nice engine at a very competitive cost with supersavers club. No more information availble...don't ask (you know what happens eventually to most Revolvers!)