Abstract: The muffler comprises a tubular shell which is internally lined with a noise-deadening material and is closed at its ends by a front wall provided with an inlet connectable to receive exhaust gas, and by a rear wall. A first chamber and a second chamber, which are separated by a transverse wall having an inlet opening and an outlet opening, are defined within the tubular shell. A perforated inlet pipe extends within first chamber from the inlet to the inlet opening. Gas-piping elements extend within the first chamber and have one end open to the outlet opening, and another end connectable to the exhaust pipes. The inlet opening and the outlet opening are substantially equal in diameter to the inlet pipe, and are interconnected via a toroidal duct that is arranged within the second chamber and is substantially equal in diameter to the inlet pipe.

Abstract: A plurality of pipes adapted to be jointed to the exhaust ports of one line of an engine are joined together into a manifold comprising an equal number of pipe stubs, each receiving one of said pipes. The pipe stubs lead to a box from which extends a conduit that is jointable to terminal parts of the exhaust system, and each of them is flared at its jointed end, against which an annular gasket surrounding the respective pipe is pressed to abut by elastic elements.