Performance is absolutely not an issue. A one cylinder water cooled KX80 Kawasaki dirt bike motor being used in a fun scooter project. The 2 stroke it's replacing is rated at 2.5hp. The KX80 weighs the same (actually a few oz less!) and is rated at 16hp. I'd be very happy with 8hp if I could make it stealth quiet. Seems like it would be possible, especially being water cooled, with a standard (non expansion) enduro muffler and a little more attention paid to silencing the intake. Would I have to do any retuning to the engine? Anyone ever tried to calm a two stroke beast? Just how quiet can you get these things? I had a Yamaha 80cc "Mini Trail" when I was a kid. That's how quiet I'd like this to be. Obviously I want more than 2.5 hp out of it or it's not worth the effort. An enduro pipe would probably spread out the power band a little bit as well, no?