hey, we're not trying to be @$$holes to you here. The idea sounds like fun, i agree, but not at the cost of your freedom or juvenile record. (sorry for calling you a "juvenile" but you ARE still a minor) But this is a really bad move, IMHO. Even if you never used them on public roads, simply being pulled over with that setup ("wig-wag" lights i think they're called) in your car is going to cause you a lot of problems. And in that stiuation, the police arrest people first and ask questions later, much to your expense and dismay. You are not a cop, dont try to act like one.
Oh, and don't do stupid stuff just because you're a "minor;" being underage doesn't grant you immunity and ignorance is no excuse in court.