Actually, I saw this topic and checked for the upcoming trip, and some municipalities do have a law that states that anything louder than originally installed from the factory is illegal. I saw another township that set the limit at 74 dB(A) measured at 50 feet from the rear of the vehicle (which is entirely too low). Some other ones have a really vague statute that states that "any noise that can reasonably disturb a person more than 50 feet from the vehicle, including radio, exhaust, blah blah ..."
I didn't find the state statutes, but it looks like some local governments have adopted laws that are tougher than the state's limit. Of course, if true about "louder than stock", they would have to prove that fact if taken to court, since the burden of proof is on the prosecution.
Another interesting point in this thread is that the MI tint law does not apply to cars registered in other states. Good thing to know for our out-of-state brethren that have tint and will be tooling around MI this weekend. (Not that it applies to me.)
