Thats a ambitious theme to go for. But keep in mind, most of the board members here do not share the same view as you. And its not like you have made this clear yet. Is the entire car going that train theme?
As a locomotive guy, you know depending on where you live, there are decible levels one needs to abide by for noise pollution. Along with the neon plate, you are drawing more attention to yourself than more you want. Seriously, my wife is an insurance agent, and suggests you may be liable if you cause you accident if you startle someone with a non standard car horn, especially with that magnitude. Its all about safety bottom line.