Muffler

A muffler comprising:

• an upper case provided at the opposite ends with semi-cylindrical inlet and outlet sections respectively and having an outwardly raised central portion and an integral flange-like edge portion;
• a lower case joined at a flange-like edge portion to that of said upper case and substantially symmetrical with said upper case with respect to the underside thereof;
• an exhaust inlet tube forming member having at least a semi-cylindrical inlet section inserted in a cylindrical inlet formed by the inlet sections of said upper and lower cases joined together and a guide section connected to said inlet section and being joined to said upper case when said guide section is semi-cylindrical and to both said cases when said guide section is other than semi-cylindrical, said forming member being provided adjacent to an end thereof with a perforated portion;
• and
• an exhaust outlet tube forming member having at least a semi-cylindrical outlet section fitted in a cylindrical outlet formed by the outlet sections of said upper and lower cases and a guide section connected to said outlet section and being joined to said lower case when said guide section is semi-cylindrical and independent of said inlet tube forming member and to both said cases when said guide section is other than semi-cylindrical;
• the exhaust inlet and outlet tubes formed in this way within the muffler body being in communication with each other through an exhaust gas passage formed between the outer surface of said inlet and outlet tube forming members and the inner surface of said upper and lower cases, the lengths of said inlet and outlet tubes within the muffler body being in spatially overlapping relationship.