In Michigan they only check quads and four strokes on the trails, but if you ask they will check your two stroke bike. The Bull Gap area and Silver Lake are the only places I am aware that check the noise levels. They allow 96 decibels but 94 is the rule my silencer was three years old and still came in at 97, they simply suggest to repack and tell you to ride safe. I have been stopped in my truck at Silver Lake for a check but since they check at 2500 RPM, mine passes just fine. ( it would never pass at 4500 RPM )
John