Tennessee Code Title 55. Motor and Other Vehicles § 55-9-202

(a) It is unlawful for a person to drive a motor vehicle on a road, street, or highway if the motor vehicle is not equipped with a muffler in good working order and in constant operation. A motor vehicle's muffler is deemed to be not in good working order or in constant operation if the motor vehicle produces excessive or unusual noise or annoying smoke.

(b) It is unlawful to use a “muffler cutout” on any motor vehicle upon any road, street or highway.

(c) This section does not apply to farm tractors or implements of husbandry, as those terms are defined in § 55-8-101.

(d) For purposes of this section, “excessive or unusual noise” includes motor noise emitted by a motor vehicle, other than a motorcycle, that is noticeably louder than similar vehicles in the environment and a sound pressure level in excess of ninety-five decibels (95 dB).

(e) It is a defense to prosecution regarding excessive or unusual noise if the person provides satisfactory evidence that the vehicle's muffler does not emit noise in excess of ninety-five decibels (95 dB) as measured in accordance with applicable standards and specifications outlined by the Society of Automotive Engineers.

(f) A violation of this section is a Class C misdemeanor.