Motorcycle exhaust system

An exhaust system for a motorcycle engine which comprises:

• a. an outer tubular imperforate casing having a substantially elliptical cross section throughout its length with a ratio of minor to major axes from 0.70 to 0.85;
• b. an inner tubular, perforate sleeve also having a substantially elliptical cross section throughout its length with substantially the same ratio of minor to major axes and concentrically received within said outer casing to form an elliptical annulus therebetween;
• c. gas permeable, high temperature resistance inert packing disposed within said elliptical annulus;
• d. single-piece inlet and outlet end caps, each having a sleeve with an integral elliptical flange having a dependent ellipsoidal skirt with the opposite ends of said outer casing received over and secured to said skirts, and with each of said end caps having inner support members with the opposite ends of said inner perforate sleeve received against said inner support members, thereby positioning said inner perforate sleeve in concentric alignment to said outer casing.