Light weight hybrid exhaust muffler

A method for forming an exhaust system assembly, said method comprising the following steps:

• forming first and second external shells such that each said external shell comprises a peripheral portion dimensioned and configured such that the peripheral portion of the first external shell can be placed generally in register with the peripheral portion of the second external shell, the forming of said external shells further defining a plurality of chambers extending from the peripheral portions, with each said external shell comprising at least one baffle crease unitary with said external shell and separating the chambers therein, said baffle creases being formed to extend between spaced apart locations on said peripheral portions and comprising generally planar portions and generally nonplanar portions dimensioned to engage at least one pipe, the planar portions of each baffle crease in the first external shell being disposed to be placed generally in register with the planar portions of the respective baffle crease in the second external shell, said first and second external shells further being formed to define at least one inlet for receiving an exhaust pipe and at least one outlet for receiving a tail pipe;
• positioning the first and second external shells generally in register with one another;
• securely connecting said first and second external shells to one another;
• providing an elongated exhaust pipe having opposed first and second ends and an elongated tail pipe having opposed first and second ends;
• forming aperture means in at least one of said exhaust pipe and said tail pipe in proximity to the first end thereof for permitting expansion of exhaust gas therefrom;
• slidably inserting the first end of said exhaust pipe and the first end of said tail pipe into the respective inlet and outlet openings of said muffler at least a sufficient distance for the respective inlet and outlet pipes to be supported by at least one of said nonplanar portions of said baffle creases and a sufficient distance for the aperture means to be disposed in the muffler, the second ends of said exhaust pipe and said tail pipe being disposed externally of said muffler;
• and
• securely connecting portions of said exhaust pipe and said tail pipe intermediate the respective ends thereof to at least one of said external shells generally adjacent the respective inlet and outlet thereto.