Kudos to them, I hope they set up roadblocks to check every motorcycle that comes through town.

That said, this will be nearly unenforceable. For example: If you buy a Mustang, you can get the GT350R with the flat-plane V8 that is quite literally a street legal race car and it sounds like it. Or you can get that same Mustang with a turbo 4 cylinder engine. The 4 cylinder car will be about as loud as the average Toyota Camry. Will all officers be trained to know every car model? Will they be trained to know what is "stock" on the cars? What about factory and dealer-installed options? Are those legal?