I just got a letter today from cat that said, All F5 and F7 and Mountain Cat 900 and all snopros L/C and fan have to loud of exhaust. It says your suppose to go to you dealer and order a sound reduction update kit. It says these sleds dont comply with the sound level requirments of the Snowmobile Safety and Certification Committee. (SSCC). What's this all about, i put a silencer on mine because i thought is was not loud enough.