Typically the smoother an exhaust pulse is, the less rowdy it sounds. Which is why a Subaru Rumbles like a small block and a civic purrs. The Subaru motor uses unequal length headers in stock form. The Grom being a single cylinder has a lot of time between exhaust pulses, which makes it sound like a much bigger bike than 125cc. It also makes it loud if you don't baffle it effectively. So anything that makes any power will be drastically louder than stock. You will have to compromise between power and sound, hopefully the DB killer will help you out. Look at @tooter , he has built some awesome exhaust and DB killers that might interest you. Sorry for the hijack.....Sweet lawd almighty! Can an exhaust be any louder? I ordered a DB Killer, will that bring it down enough to not wake up the dead? I've run Kerker and Yosh pipes on other bikes, but sweet jazuus, this thing is loud. It gave me a headache, just going to top off the tank. I really hope this DB Killer helps, or it has to go.