Abstract: A powerboat muffler is disclosed that balances decreasing exhaust noise and producing power. A muffler cannister has concentric inlet tubes, forming an inlet baffle, where exhaust gas and engine coolant enters the muffler, a V-shaped baffle within the cannister, a funneled outlet, and concentric outlet tubes, forming an outlet baffle. The inlet baffle comprises concentric outer and inner tubes and the front wall of the muffler, which together form an toroidal inlet space. The inner inlet tube extends a certain distance into the muffler cannister. The inside wall of the inner inlet tube is shaped to create a venturi. Through the front wall, within the toroidal inlet space, small venturi-shaped openings are disposed radially between the outer and inner tubes to allow engine exhaust and coolant to enter the muffler. At the outlet end of the muffler, a tapered nozzle funnels exhaust to an outlet tube with a venturi contour. The outlet tube extends out from the outlet nozzle a certain distance.