That would be legit. Are those legal?…. Eh, who cares. Love the idea.

I had one in high school and did all sorts of dumb stuff with it and never got arrested, so it must be legal. It was just a CB radio with a PA function, hooked to a paging speaker mounted behind the grill.

They have scrolling led lights that you can write from your phone. Silent and effective.

Guess you kinda need to drive a certain way though..