This simonini circuit pipe can be a nice little blasty pipe but it takes a little bit of work. In the header of the pipe you’ll find a little restrictor that can easily be dremeled out. Once that’s out the pipe will be pretty usable, strong low and mid range.
That said there’s still some restriction in the pipe. I’m used to seeing silencers formed off the stinger by a perforated tube surrounded by fiberglass. This one uses a different design. It’s just two 2 short offset pipes. The stinger has an internal diameter of roughly 13mm and the pipes in the silencer are one 9mm. As the bike get’s into the higher rpms it’s unable to bleed off the exaust the bike is generating and you hit a wall.
I kept the design of the silencer the same on mine and I replaced the small 9mm pipe with some bigger ones that were closer to 17mm. I figured they still serve their purpose of quieting things down, but would no longer serve as a limiting factor.
Well that did the trick, it’s only slightly louder I still have decent low-end and the bike doesn’t hit a wall when accelerating anymore.