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A. Every motor vehicle 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 cutout, bypass, or similar device upon a motor vehicle on a highway. When any motor vehicle was originally equipped with a noise suppressing system or when any motor vehicle is required by law or regulation of this state or the federal government to have a noise suppressing system, that system shall be maintained in good working order, and no person shall disconnect any part of that system except temporarily in order to make repairs, replacements or adjustments, and no person shall modify or alter that system or its operation in any manner, except to conform to the manufacturer's specifications. No person shall knowingly operate and no owner shall knowingly cause or permit to be operated any motor vehicle originally equipped or required by any law or regulation of this state or the federal government to be equipped with a noise suppressing system while any part of that system is disconnected or while that system or its operation is modified or altered in any manner, except to conform to the manufacturer's specifications.
"Excessive or unusual noise" as used in this section includes, but is not limited to, any sound made by a passenger motor vehicle or a motorcycle at any time under any condition of grade, speed, acceleration or deceleration, which exceeds ninety two (92) decibels, or any lower decibel level than is fixed by law or the rules and regulations regularly adopted by the board of health and welfare, on the A scale of a general radio company no. 1551-B sound level meter, or equivalent, stationed at a distance of not less than twenty feet (20') to the side of such vehicle or motorcycle as such vehicle or motorcycle passes the soundmeter or is stationed not less than twenty feet (20') from a stationary motor or engine.
B. The engine and power mechanism of every motor vehicle shall be so equipped and adjusted as to prevent the escape of excessive fumes or smoke.
C. No person shall modify the exhaust system of a motor vehicle or a motorcycle in a manner which will amplify or increase the noise of such vehicle or motorcycle above that emitted by the muffler originally installed on the vehicle by the manufacturer.
D. A showing that the sound made by a passenger motor vehicle or motorcycle exceeds the maximum allowable decibel level shall be prima facie evidence of a violation of subsection A of this section.
E. No person shall sell, offer for sale, or install any noise suppressing system or device which will produce "excessive or unusual noise" as defined in subsection A of this section. (1977 Code)