Optional Sound Reducing Baffles for the BUB Straight Away and Lakester system on XL models. These baffles will reduce the overall sound level by 4 to 6 decibel points. The Sound Reducing Baffles create increased back pressure resulting in improved torque and low end performance. This product is designed for use on closed course competition motorcycles only. Click Here for More Information http://www.bub.com/Emissions_Information.cfm