An exhaust sound attenuation and control system combines the functions of a muffler and resonator in a single, relatively compact device. The internal components of the device may also be coated with one or more emission reduction materials to provide a catalyzing function for the exhaust gases flowing through the system. The present exhaust system provides multiple gas flow paths therethrough, with different paths producing different effects in order to reduce sound output at certain frequencies, as in a resonator, and to attenuate sound throughout a broader frequency range, as in a muffler. The cross-sectional areas of each of the various internal passages and outlet pipe are at least as great, or greater, than the cross-sectional area of the inlet pipe, thereby providing a free flow system with relatively low backpressure.