Found some louisiana laws, this sucks
§352. Mufflers; requirements; prevention of excessive noise, fumes and smoke
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.
B. No person shall use a muffler cut-out, bypass or similar device upon a motor vehicle on a highway of this state.
C. 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.
Acts 1962, No. 310, §1.
§353. Modification of exhaust systems
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 such vehicle, above that emitted by the muffler originally installed on the vehicle and the original muffler shall comply with all of the requirements of R.S. 32:352.
Acts 1962, No. 310, §1.