I stick to the limits when going through towns/villages, but of course just like car drivers, there's always going to be some muppets that don't.
As for the loudness, i'm afraid that's something you can't fix really, minus the police pulling every biker over and checking, even then you'd have to do the cars too.
For a biker like myself i have a loud system, it's a safety feature and saved my bacon a few times.
Of course i can understand it being an issue for you though, i'd grin an bare the sound, but by all means report vehicles (not just bikes) that speed.