i agree 10,000% on the Harley exhaust noise enforcement.
i live down the street from a biker bar. the exhaust noise gets pretty bad.

i do live next to a county highway. i accept SOME of the noise from living next to the highway. but there should be limits.
there are a LOT of cars drive by my house WFO 75+ mph, yet the limit is 35mph and no one seems to get a ticket, straight piped with no mufflers. the noise is extreme.

i would suggest a law anyone with a loud muffler should be required to sit 10' directly behind their car, no ear plugs allowed, in a chair and someone runs it thru thru rpm range and hold it at WOT for 10 seconds. they go thru the cycle for 5 min. they will be required to do this every week as long as they drive the car.
there will be a LOT of people with severe hearing problems or a bunch of quiet cars.