A brand of disc mufflers for cars, motorcyles and ATVs proven to make power by creating a scavenging effect in the exhaust system. The gap between each disc in the muffler ranges from .023-in. wide on the inside to .028-in. on the external open edge. As hot exhaust gases pass through the discs to exit the muffler, they enter a larger area, creating a slight pressure drop as the gas expands, creating a scavenging effect for the hot gas still inside the muffler. Adding discs increases the size of the exhaust outlet area. Removing discs decreases the exhaust outlet surface area.