MICHIGAN

Code Section 707, 707c

Loud Exhaust

While it is difficult to determine whether a motorcycle is exceeding the decibel levels found in MCL 257.707c(1)(b) as it passes at 55 or 70 mph, there are other sections that are enforceable without a decibel meter. MCL 257.707(1) prohibits the operation of a motor vehicle with exhaust that is not "in good working order and in constant operation to prevent excessive or unusual noise and annoying smoke," if the baffles in the muffler have been removed, destroyed, or damaged, or the motorcycle is equipped with a cutout, bypass, or similar device. MCL 257.707c(3) also prohibits the operation if the motorcycle "is not equipped with a muffler or other noise dissipative device, or is equipped with a cutout, bypass, amplifier, or similar device." MCL 257.707b requires that a motorcycle be "equipped with an exhaust system in good working order to prevent excessive or unusual noise." Type "motorcycle exhaust" into any search engine to link to numerous sites offering instruction and tips on making motorcycles louder.

Enforcement action can also be taken under MCL 257.707c(2), (4), (5), or (6) against the person or dealership that either modifies the exhaust or sells a motorcycle with loud or modified exhaust, while MCL 257.707d also makes the person who modifies the exhaust civilly responsible if the operator receives a citation.

Again all this extra wording could be eliminated by inserting the phrase:
 "Factory Installed or Equivalent!

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257.707c Noise limitations; prohibitions.

(b) A motorcycle or a moped:

i) Eighty-six DBA if the maximum lawful speed on the highway or street is greater than 35 miles per hour.
(ii) Eighty-two DBA if the maximum lawful speed on the highway or street is not more than 35 miles per hour.
(iii) Ninety-five DBA under stationary run-up test at 75 inches.

(c) A motor vehicle or a combination of vehicles towed by a motor vehicle not covered in subdivision (a) or (b):

(i) Eighty-two DBA if the maximum lawful speed on the highway or street is greater than 35 miles per hour.

(ii) Seventy-six DBA if the maximum lawful speed on the highway or street is not more than 35 miles per hour.

(iii) Ninety-five DBA under stationary run-up test 20 inches from the end of the tailpipe.

(2) A dealer shall not sell or offer for sale for use upon a street or highway in this state a new motor vehicle manufactured after April 1, 1978, which produces a maximum noise exceeding the following limits:

(a) A motor vehicle with a gross vehicle weight rating of 8,500 pounds or more—83 DBA.

(b) A motorcycle or a moped—83 DBA.

(c) A motor vehicle not covered in subdivision (a) or (b)—80 DBA.

(3) A person shall not operate a vehicle on a highway or street if the vehicle has a defect in the exhaust system which affects sound reduction, is not equipped with a muffler or other noise dissipative device, or is equipped with a cutout, bypass, amplifier, or a similar device.

(4) A person, either acting for himself or herself or as the agent or employee of another, shall not sell, install, or replace a muffler or exhaust part that causes the motor vehicle to which the muffler or exhaust part is attached to exceed the noise limits established by this act or a rule promulgated under this act.

(5) A person shall not modify, repair, replace, or remove a part of an exhaust system causing the motor vehicle to which the system is attached to produce noise in excess of the levels established by this act, or operate a motor vehicle so altered on a street or highway.

(6) A dealer shall not sell a used or secondhand motor vehicle for use upon a street or highway which is not in compliance with this act.

History: Add. 1978, Act 73, Imd. Eff. Mar. 21, 1978 ;-- Am. 1978, Act 492, Imd. Eff. Dec. 1, 1978

My God do you believe this double talk?  
Every State so far has the same enforcement language!