The Dynomax VT muffler is a revolutionary, high-flow straight-through stainless steel performance muffler that controls irritating drone while ensuring maximum performance. Valve Technology Mufflers feature an exclusive, precisely calibrated internal valve that redirects exhaust flow, during cruising conditions, to provide Drone-Free Performance. Hammer the gas and the valve automatically adjusts for maximum exhaust flow, delivering on-demand performance and a deep, throaty drone-free sound.