Cops in Michigan apparently dont like loud 273 exhaust

I had a friend in Pa with an AAR Cuda that had to get paperwork from Chrysler to show in court that factory designed the exhaust that way. It was the only way he got out of loud and faulty exhaust ticket.
In '70, when I picked up my new AAR, the mufflers(IIRC) and side exhaust (definitely), came in boxes in the trunk. There was a printed sheet with the stuff in the trunk, saying that in some states the exhaust has to run out the back end, and the side exit exhaust might be illegal, so you have to substitute other parts if that were the case.