"Starting Line Products Super Silent Muffler This muffler for the Polaris RZR is an incredible 5 decibels quieter than stock while providing a 41% increase in airflow (20 more cfm) for more power. The subtle sound of this muffler provides a relaxing environment for the rider and passenger to carry on a conversation easily while under way, not to mention the benefit to others in the surrounding area. Whether you are using your RZR to get you in and out of your favorite hunting spots, or just want to have a more enjoyable ride with less noise, this muffler is perfect for you. Features a removable Forest Service approved spark arrestor. 2009 standard RZR and 2009 RZR-s will require the rear differential stabilizer.