I use to use screen in my pipes till one dnr would not let me go in because i did not have a stamped usf approved spark arrestor on my silencer--i got away with that for 2 years. i have new silencers and have no problem now. If they check your noise level(only when busy) just dont rev the piss out of it. Mine hit 87db and i barely gave it any gas! Buy day sticjkers to since its late in the year-like 8 bucks