Just a few points from what I read here.....
1. It is illegal.. but for it to be enforced, the cops need to carry a dB meter so they can have proof of it, so most cops don't even bother. BUT in some towns/cities they have by-laws that say something along the lines of "sound that can be heard from more than X blocks" and usually in those cities the cops are much more active.
2. Wattage is highly overrated.. you might think that they're pumping out tens of thousands of watts but in reality, it's really not that much. For ex.: one of my friend has a 1000W amp with a 15" sub..... pushing out 145dB (please note that a Jet engine at 3m is pushing out only 140dB and that the threshold of pain is somewhere between 120-130dB). Most cars that have more than 5000W of power will actually need reinforced plexi-glass instead of the glass window just because of the sound pressure, they'd blow out... and NO ONE can stay in a car at that volume.. unless you like bleeding from your ears and throwing up all over yourself...
3. Hearing loss is mostly caused by higher frequencies... The frequencies used for 'boom boom' will just make you sick.
I just wanted to say a little something about it.. figured I should try to get my post count up
As a sound tech on 'permanent vacation' now, I've had my share of loud concerts and I know I lost some of my hearing.. considering I'm only 23, it kinda sucks. The thing I hate the most is when you get that "sound of silence" thing going... arrggh It drives me crazy!