N.D. Cent. Code § 39-21-37 (2025)
1. Every motor vehicle must 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 may use a muffler cutout, bypass, or similar device upon a motor vehicle on a highway.
2. The engine and power mechanism of every motor vehicle must be so equipped and adjusted as to prevent the escape of excessive fumes or smoke.