W. Va. Code § 17C-15-34: Mufflers; prevention of 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. Such muffler shall be the muffler originally installed by the manufacturer of the vehicle or, if a replacement, the equivalent thereof. No person shall use a muffler cutout, bypass, or similar device upon a motor vehicle on a highway.

(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.