I'm asking because the last race I was in I had to install a spark arrestor in my silencer. Each bike was actually checked at the registration area. Since then, I just left the arrestor in place as I have to remove & disassemble the silencer to remove it. I'm just wondering what kind of effect the arrestor will have on engine performance, if any. I personally did not notice any changes in how the bike performs other than a little bit more splooge then usual. Maybe that's because the screen is catching more and allowing it to run down the silencer tip as opposed to most of it just being blown out with the hot exhaust gasses? Should I remove it, or leave it in? Anyway, interested in you guys opinions.