Starting Line Products Performance Slip-On 09-106 Slip-On Muffler by Starting Line Products This performance slip-on silencer for the Polaris RZR is designed for maximum airflow without substantially increasing sound level output. It provides a 79% increase in airflow over the stock silencer. This results in a substantial performance improvement, showing better throttle response as well as top-end horsepower. The sound levels are within 2 decibels of stock (90 dBA on SAE J1287 test) for a trail friendly performance silencer.