Wyo. Stat. § 31-5-953 (2026)

(a) Every vehicle shall be equipped, maintained and
operated so as to prevent excessive or unusual noise. Every
motor vehicle shall at all times be equipped with a muffler or
other effective noise suppressing system in good working order
and in constant operation. No person shall use a muffler
cut-out, bypass or similar device.

     (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) This section applies to motorcycles, motor-driven
cycles, multipurpose vehicles, mopeds and off-road recreational
vehicles as defined by W.S. 31-1-101(a)(xv)(K)(II) that are
registered pursuant to W.S. 31-2-232 and off-road recreational
vehicles as defined by W.S. 31-1-101(a)(xv)(K) that are operated
pursuant to W.S. 31-5-1601.