So you know-any aftermarket exhaust is going to be a straight through pipe, meaning it will be
much louder than stock. I'm not sure how loud the NHRC pipe is, but generally we're talking loud enough that you're doing damage to your ears, without plugs.
Kycmo is gy6 based. Most gy6 mufflers and headers will fit your p150; bracket points might be different. Spend at least 250 on an exhaust. Guaranteed you will end up spending more than 300 dollars, on 100 dollar exhausts, because they
will break. Even a 250 dollar exhaust will end up breaking. Unless you have a welder, spend the 300 outright and save yourself a headache; or just get a stable quiet pipe and go stock.
Here's the best aftermarket muffler.
http://www.scooterelements.ecrater.com/p/15893679/vento-hurricane-150-vale-complete-exhaustJust remember, when you put a new exhaust on your engine will be breathing better, and therefore be running lean. Do not run your engine lean. This will cause your parts to heat up faster and hotter. Increase the main jet before you even run it. Then continue to rejet until it's right.