by Mike Mavrigian
(Taken from Performance Exhaust Systems by Mike Mavrigian)
The purpose of a muffler is to aid in managing the engine’s exhaust sound level, and to “tune” exhaust tone. While some view the use of mufflers as simply a necessary evil, in terms of controlling engine exhaust noise level, mufflers provide an additional engine tuning aid in terms of horsepower and torque, primarily for street-driven vehicles that must operate and perform in a wide range of vehicle and engine speeds.
For the sake of illustrative comparison, consider a firearm’s silencer. This device attaches to the gun-barrel exit in order to decrease the audible noise created by the explosive discharge. Contrary to the popular term, this device does not “silence” the discharge. Rather, it suppresses the noise, so the proper term for this device would be a suppressor, not a silencer. The same holds true for an automotive exhaust system’s muffler. Instead of silencing or eliminating the exhaust noise, the muffler suppresses the exhaust note. The design of the muffler has a direct effect on both the level of noise and the tone of the engine’s exhaust.
Round-profile canister, or bullet-style, mufflers offer both excellent straight-through flow and a reduced profile for exhaust routing where space is at a premium. (Photo Courtesy Borla Performance Industries)
Performance muffler designers invest an incredible amount of time in developing mufflers that reduce noise levels while providing minimal flow restriction. (Photo Courtesy Flowmaster)