Set up a shooting range between your houses? Just follow the basic safety rules, and if you're out of town enough that his music doesn't bring any legal help, he obviously wouldn't mind you making your own type of noise.
That's tongue-in-cheek, of course... mostly anyway. His parents aren't the ones making the noise, but they also aren't doing anything to stop it evidently. Whether or not there's a legal authority involved, he is infringing on your rights to quiet enjoyment of your property. I don't know what the legal environment is there insofar as suing for this, but possibly some (harmless) shenanigans would be a nice next step. I bet he'd hate to walk out to his truck to find his tires unexpectedly emptied of air... which can, as we know, be done without damaging the tires.