The performance of stainless steel (SS) powder metallurgy (P/M) materials in automotive exhaust system applications continues to be a subject of interest. Reported within are results of several investigations into the properties of several P/M stainless steel alloys at elevated temperatures. Elevated temperature tensile testing was conducted to determine the strength of P/M alloys at exhaust system operating conditions. Cyclical elevated temperature corrosion/oxidation/quench testing was also conducted to determine corrosion/oxidation performance of various alloys in exhaust system environments. Both 300 and 400 series alloys, as well as some specially modified and specially processed alloys, were subjected to the above tests. Various processing parameters were used to illustrate the dramatic effects of processing on material performance. Recommendations are provided for alloy selection and alloy properties in exhaust system applications.