Section 4523 - Exhaust systems, mufflers and noise control(a) Compliance with established sound levels.--Every motor vehicle operated on a highway shall be constructed, equipped, maintained and operated so as not to exceed the sound level for the vehicle as prescribed in regulations promulgated by the department. The test procedures and instrumentation to be utilized shall also be established by regulation.(b) Compliance with exhaust requirements.--In addition to any requirements established under sections 4531 (relating to emission control systems) and 4532 (relating to smoke control for diesel-powered motor vehicles), every motor vehicle shall be constructed, equipped, maintained and operated so as to prevent engine exhaust gases from penetrating and collecting in any part of the vehicle occupied by the driver or passengers.(c) Mufflers and related equipment.--Every motor vehicle shall be equipped with a muffler or other effective noise suppressing system in good working order and in constant operation and no muffler or exhaust system shall be equipped with a cutout, bypass or similar device.(d) Unauthorized modification of equipment.--No person shall modify the exhaust system of a motor vehicle in a manner which will amplify or increase the noise emitted by the motor of the vehicle above the maximum levels permitted under subsection (a) or violate the provisions of subsection (b). Headers and side exhausts are permitted provided the vehicle meets all the requirements of this section.(e) Fire equipment and racing vehicles.--This section does not apply to fire equipment or to racing vehicles being operated in an organized racing or competitive event conducted under a permit issued by local authorities. 1976, June 17, P.L. 162, No. 81, § 1, effective 7/1/1977.