DG Performance 051-4300 - RCM II Slip-On (Black) for Yamaha Rhino 660 (2004-2007 ) RCM II - The best value in the ATV Industry! This slip-on offers increased throttle response, more power and torque Features a durable 4 inch dia. round steel muffler body Repackable muffle - Standard sound level is aprox. 98 db. DG offers 4 different Quiet Core Inserts to reduce exhaust sound. Equipped with a US Forestry approved spark arrestor. This Lightweight Slip-On weighs approximately 6.5 lbs Constructed from 16 ga. Mild steel tubing.