The topic of exhaust noise is an involved one. Over the last 30 years or so, federal, state and local rules and regulations have been introduced to control exhaust noise levels in the United States, but exact limits--in terms of decibels (dB)--may not be specified. Legislation proposed by the Speciality Equipment Market Association (SEMA), limiting exhaust noise to 95dB, has been implemented in some states but not others. There are also a number of consumer groups who actively campaign for reductions in exhaust noise.
The principle statute regarding exhaust noise in New Jersey states that, “Every motor vehicle having a combustion motor shall at all times be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise and annoying smoke, and no person shall use a muffler cut-out, bypass or similar device upon a motor vehicle on a highway.” It goes on to describe a muffler as a correctly functioning device or system that reduces engine noise, but no actual decibel limit is specified.
Similarly, regulations in New York state, “Every motor vehicle, operated or driven upon the highways of the state, shall at all times be equipped with an adequate muffler and exhaust system in constant operation and properly maintained to prevent any excessive or unusual noise and no such muffler or exhaust system shall be equipped with a cut-out, bypass, or similar device.” Once again, no actual decibel limit is specified, but the regulations also expressly forbid modifying the muffler or exhaust system so that it is louder than the original system. Law enforcement officers in New York do not carry sound meters, but based on the judgment of individual officers, motorists can be cited if the noise from a vehicle exhaust can be heard clearly at a distance of 150 feet.
The Georgia Code states, “Every motor vehicle shall at all times be equipped with an exhaust system, in good working order and in constant operation,” without specifying a decibel limit, but goes on to detail what is, and what is not, permissible in the specification of an exhaust system. It is, for example, illegal to use or sell mufflers which cause unusual or annoying noise, or muffler cutout, bypass or other similar devices.
