Think big picture.. This has nothing to do with just exhaust, but what you have to wear, where you can ride, when you can ride, or even IF you can ride..
Keep drawing bad attention to motorcycles, and they'll enact laws such as that you have to have headlights on at all times, have to wear helmets, have to have stock exhaust, have to wear protective eye wear, etc... Oh, that's right, they've already enacted those laws, and have tried to enact more that haven't passed, YET...
As I mentioned before, loud exhaust affects everyone around the motorcycle. Small children, old people, or anyone that doesn't want to hear a loud motorcycle.. They bitch to law makers (who have nothing better to do than protect us from ourselves) and the next thing you know, there's horsepower limits, tiered licensing, mandatory gear, limits on hours of operation, NOISE LIMITS, or just an overall banning of motorcycles..
I know.. Sounds far fetched.. But is it??