Abstract: The present invention provides a muffler which has an outlet tube with a funnel shaped element having a large diameter end positioned in an expansion chamber and conically tapering to a junction with a cylindrical neck element extending into an inlet end of an outlet tube. An inlet tube is supported by an outer shell which also supports the outlet tube. The inlet tube is attached to the outer shell by a first partition and a first end cap, forming a tuning chamber. The outlet tube is attached to the outer shell by the funnel shaped element and a second end cap, forming an outlet chamber. A space defined by the distance between the first partition and the second partition and the geometry of the outer shell forms an expansion chamber. The three different chambers serve to either tune or quiet the exhaust coming from an internal combustion engine, and the funnel shaped element serves to smooth the flow of exhaust from the inlet tube to the outlet tube.

Abstract: A flat, box-like muffler formed of metal upper and lower housing sections and internal gas passage defining plates has drainage holes to allow liquid that collects on the top of the muffler or on the bottom of the lower section inside the housing to drain out of the muffler. A special sound attenuation structure comprising passages pressed in the plates and support channels in the housing sections is shown.

Abstract: An exhaust silencing device comprises an outer tube that is pinched down to form a series of annular chambers around a coaxial inner gas flow tube and has openings connecting the chambers to provide for some secondary gas flow parallel to primary flow through the tube. The device and is shown in conjunction with a catalytic converter to provide an exhaust system that has a sporty sound.