Some observations:
Noise is noise. It doesn't matter if it comes from a motorcycle, a chainsaw, or a beat-up Honda Civic with a bolt-on rear spoiler and 4x15" subs. There shouldn't HAVE TO be a law against this sort of thing, it should just be common courtesy, but unfortunately there are those who will do whatever they feel they can get away with.
When I was a kid in the 60's, motorcycles had an aura of the rebel about them. The "bad boys" rode them and they were the sort of people "nice folks" avoided. If my observations of the last few years are any indication, nowadays a motorcycle brings to mind a middle aged accountant or similar who is desperately seeking that same "bad ass" image that he remembers from his youth. A symbol of rebellion has gone main-stream, and thus, no longer denotes anything rebellious. Heck, no anti-social rebel could hope to afford some of the tricked-out custom jobs I've seen. My guess is that a portion of the biker population buys into the loud pipes aspect in order to feed the rebel fantasy. I can only imagine that this "infiltration" must really piss-off the genuine old-school biker types.
Don't get me wrong, I've got nothing against bikes per se, but I find this reversal of image to be mildly entertaining in a sardonically ironic way. Further, I think there are few images on the road more sad than seeing some obese guy driving a custom trike. All the disadvantages of a car with none of the advantages of a bike. The last time I rode a vehicle with three wheels I wasn't even in kindergarden. Any day now I expect to someone driving a motorcycle with training wheels.
Rebel without a cause, indeed.