Abstract: A muffler for an internal combustion engine having: (a) a housing including: (i) an inlet opening formed for a flow of exhaust gas into the housing, (ii) an outlet opening formed for a discharge of exhaust gas from the housing, and (b) inner workings disposed within the housing, including: (i) a dome-shaped partition with a first end of the surface pointing toward the inlet opening, and widening out at a second end to form a base, the dome-shaped partition having at least two partition openings disposed between the first end and the second end of the exterior surface, wherein the dome-shaped partition is disposed within the housing such that substantially all of the exhaust gas is directed through the partition openings and into an interior of the dome-shaped partition, before being discharged through the outlet opening.

Abstract: A muffler for an internal combustion engine having characteristically low back pressure and a pleasing sound is disclosed. The muffler comprises: (a) an elongated housing having an interior wall and including: (i) an inlet opening formed for the flow of exhaust gas into the housing, and (ii) an outlet opening formed for the discharge of exhaust gas from the housing; and (b) a partition shaped like a hollow pyramid, disposed in the housing and having interior surfaces and exterior surfaces, the exterior surfaces joining at a first end to form a pyramidal apex, the pyramidal apex pointing toward the inlet opening, and extending at a second end to form a rugose base, wherein the partition is disposed in the housing to form a plurality of spaces between the rugose base and the housing for the flow of exhaust gas.