Abstract: Within an exhaust duct are positioned a plurality of concentrically arranged, open ended, right cylinders supported axially within the exhaust duct, wherein each of the cylinders includes an inlet end and an exit end. The inlet ends are positioned in sequential downstream order from the outermost of the cylinders to the innermost of the cylinders. The cylinders are graduated in length sequentially with the outermost cylinder being shortest in length and the innermost cylinder being longest in length. The inlet ends of each of the cylinders provide a circular leading edge with a sawtooth conformation. An elongated smooth rod is positioned on the longitudinal axis of the exhaust duct with a downstream end of the rod providing a flared portion positioned at the mouth of the innermost of the cylinders.

Abstract: A combination recessed port of an internal combustion engine having a depth and inside diameter dimensions, and an adapter tube of a length exceeding the depth dimension of the recessed port, and an exhaust pipe having an inside diameter at least as large as the inside diameter of the recessed port and an outside diameter dimension greater than the inside diameter dimension of the recessed port provides improved engine efficiency and operation. The adapter tube is formed as an open ended cylinder providing an outer cylindrical surface having an annular lip formed medially, and a tapered annular surface at a distal end for mating with the exhaust pipe. The adapter inside diameter is smaller than the diameter of the exhaust port and is of such length as to enable exhaust flow to pass completely through the adapter prior to the next discharge.