Wisconsin Statutes Vehicles (Ch. 340 to 351) § 350.095. Noise level requirements

(1) Noise level standards; total vehicle noise. (a) Every snowmobile that is manufactured on or after July 2, 1975, and that is offered for sale or sold in this state as a new snowmobile shall be manufactured so as to limit total vehicle noise to not more than 78 decibels of A sound pressure, as measured by Society of Automotive Engineers standards.

(b) A person may not modify a snowmobile, or operate a snowmobile that has been modified, in any manner that amplifies or otherwise increases total vehicle noise above that emitted by the snowmobile as originally manufactured, regardless of date of manufacture.

(2) Noise level standards; exhaust and engine noise. (a) No snowmobile may be manufactured, sold, offered for sale, or operated unless it is equipped with a muffler in good working order.

(b) For snowmobiles manufactured after July 1, 1972, a muffler that is in good working order is one that blends the exhaust noise into the overall engine noise and is in constant operation to prevent exhaust and engine noise that exceeds the applicable noise level standards established under pars. (c) and (d).

(c) For every snowmobile manufactured after July 1, 1972, and before July 2, 1975, the noise level standard for exhaust and engine noise shall be 90 decibels as measured in accordance with the procedures established for the measurement of exhaust sound levels of stationary snowmobiles in the January 2004 Society of Automotive Engineers Standard J2567.