An adjustable-length exhaust system for use with two-cycle motors is disclosed. An insert section of pipe is interposed between a header pipe and a conventional tail pipe so that, when it is rotated, the overall length of the exhaust system is adjusted. The insert section is held in place between the tail pipe and a header extension pipe by a compressive force exerted by one or more springs attached between the header and the tail pipe. The insert features, on an end that slips over the header extension section, a series of graduated notches which mate with a protrusion, or "stop", formed on the mating end of a header extension section. This notch and stop combination determines the distance by which the insert section will be permitted to slip over the header extension section, and correspondingly, the overall length of the exhaust system.