Maine state law: vehicle noise and modified exhaust

Maine sets a statewide muffler and exhaust-noise rule in 29-A MRS Section 1912. The statute requires every motor vehicle and motorcycle operated on a public way to be 'equipped with a muffler in good working order and in constant operation' that prevents 'excessive or unusual noise.' It prohibits 'a muffler cutout, bypass or similar device' on any motor vehicle on a public way. Maine State Police and municipal officers enforce. The statute is qualitative (no statewide on-road decibel limit at idle or pass-by), but SAE-J1169 and SAE-J2825 sound-level methodologies are used in some prosecutions. Modified-exhaust 'pops and bangs' tunes, aftermarket cat-back systems without DOT certification, and motorcycle straight pipes are common enforcement targets. Loud cruising and revving may additionally support 17-A MRS Section 501-A disorderly conduct. Municipal cruising ordinances and quiet-zone designations are layered on under 30-A MRS Section 3001.

Traffic infraction under 29-A MRS Section 1912 with state-set fine schedule (typically $100-$250 first offense, with required inspection sticker correction). Repeat or egregious modified-exhaust violations may result in vehicle inspection-sticker revocation. Class E disorderly conduct is up to 6 months / $1,000.