Iowa Code Title VIII. Transportation [Chs. 306-330B] § 321G.11. Mufflers required

1. The exhaust of every internal combustion engine used in any snowmobile shall be effectively muffled by equipment constructed and used to muffle all snowmobile noise in a reasonable manner in accordance with rules adopted by the commission.

2. The commission may adopt rules with respect to the inspection of snowmobiles and testing of snowmobile mufflers.

3. A separate placard shall be affixed, permanently and conspicuously, to any new snowmobile sold or offered for sale in this state that does not meet the muffler requirements as stated above. The placard shall designate each snowmobile which does not meet the muffler requirements.

4. A snowmobile manufactured after July 1, 1975, which is sold, offered for sale or used in this state, except in an authorized special event, shall have a muffler system that limits engine noise to not more than seventy-eight decibels as measured on the “A” scale at a distance of fifty feet.