Abstract: A muffler for reducing noise associated with exhaust systems includes an assembly of exhaust tubes and drop-in baffles fixed inside channels defined in a clamshell-type muffler chamber formed from two stamp-formed mating external shells.

Abstract: A muffler assembly includes a pair of outer shells mating to define a muffler chamber and a pair of internal tuning plates mating to define inlet and outlet tubes in the muffler chamber. Drop-in baffles are used to divide the muffler chamber into an expansion chamber, a pair of exhaust turnaround chambers, and a pair of resonance chambers. The two outer shells and first tuning plates are mechanically locked together at the perimeter of the muffler assembly and the second tuning plate is piggybacked onto the first tuning plate to reduce the number of material layers included in the mechanical lock. Each of the outer shells includes one or more ribs and channels for stiffening the outer shell to reduce vibration noise and to conduct condensate developing in the muffler chamber either to a hotter region where it will vaporize or to a drain.