The big idea
Ban people modifying their cars and bikes to have louder exhausts than the ones they come with. There is no reason what so ever for these people to have loud exhausts apart from misguided vanity, yet the general public have to put up with their right to peace and quiet being removed by a few idiots. Ban this pointless modification culture now, as I'm sure it will only get worse.
Why does this matter?
This is important because there should be a right to go about your day (and night) without anti-social noise ruining your relaxation time.