Abstract: An oxidation catalytic converter system for small spark ignited engines includes a housing containing a catalyst, an inlet for receiving exhaust gases from the engine, and an outlet for discharge of the exhaust gases from the housing after passing through the catalyst. Attached to the engine exhaust is a jet pipe that extends into the inlet in noncontacting relation to the housing, whereby the catalytic converter is vibrationally isolated from the jet pipe. Surrounding the jet pipe is an annular air gap through which ambient air is drawn into the housing and mixed with the exhaust gases for enhanced cooling and catalyst performance.