Abstract: Open chamber exhaust mufflers and related methods of manufacture and use are disclosed. One embodiment of an exhaust muffler has a chamber body, absorbing material that at least dampens sound, and a retainer that retains the absorbing material against an inside surface of the chamber body and exposes an open interior chamber of the chamber body to the absorbing material. The chamber body has an inlet for receiving exhaust from an engine and an outlet for expelling exhaust gas from the exhaust muffler. The chamber body, the absorbing material, and the retainer define the open interior chamber, and the open interior chamber provides an exhaust gas flow area, for unrestricted flow of exhaust gas from the inlet to the outlet, which is larger than a gas flow area of at least one of the inlet and the outlet. An end cover of the chamber body is removable in some embodiments.