Abstract: An improved muffler for snowmobiles having multiple stages including at least one radial tubular attenuator comprising one or more flat, two-part casings, the parts being peripherally identical and configured to jointly form a plurality of passages, having bell-mouth inlets and diffuser outlets, communicating with a common central cavity. In a first embodiment, the engine exhaust is conducted axially to the central cavity and the plural passages discharge into a muffler chamber to comprise the first of several muffler attenuating stages. In a second embodiment, the engine exhaust is supplied radially. Another embodiment shows a pair of the radial tubular attenuators connected serially, the gas flow in the two sets of radial passages being in opposite directions and a second chamber being interposed between the two. A still further embodiment shows a pair of the casings jointly fed centrally with the engine exhaust.