A low thermal mass, metal monolith, catalytic converter, was tested for reducing automotive emissions for applications both as lightoff and main converters. FTP testing was carried out to measure the first four minutes of Bag 1 emissions from a 2.2l, fuel-injected Plymouth Reliant, at New York State, Automotive Emissions Laboratory, Albany (NY-AEL). The car had aproximately 17,000 miles when tested and its driving history had been catalogued by NY-AEL. Both resistively heated and non-resistive mini-converter systems were tested in series with a conventional replacement new automotive converter. The non-resistive converter reduced HC, CO and NOx emissions by more than 50%, 40% and 30%, respectively. despite excess air addition. Lightoff occurred within 10 seconds of engine start. A modified cycle exploring steady state conditions under load showed greater than 70% reduction in NOx. The resistively-heated converter system further reduced THC, CO and NOx emissions, with lightoff occurring even earlier, without any pre-crank heating. Short-term durability of the catalyst and substrate was demonstrated through SEM and micrographic testing of the substrate from the test converter. The stock converter, aged for 17,000 miles, was compared against the replacement new converter and the performance drop is reported.