The peak power of some vehicles can be limited by exhaust system backpressure contributed by a catalytic converter. A computer model was developed for flow and pressure drop in a generalized single-bed bead-bed catalytic converter to determine the sources of converter pressure drop and suggest improved designs with lower restriction. In an accompanying experimental study, pressure losses in the components of two different converters were determined in an engine-dynamometer test cell over a wide range of engine operating conditions. The measured and predicted pressure drops were in good agreement. The experience gained in this study was used to develop a low-restriction converter for truck applications.