Here in the UK I think you'll find that they can only be fitted to Vauxhall Corsa's, Citroen Saxo's and the odd Renault Clio.
As I understand it, it's a device which allows you to impose your dubious musical tastes on the the rest of us whilst sitting at traffic lights. If this is the case, I'd advise you to save your money and drive around with the windows open and the volume cranked right up
You'd be surprised how loud it goes in the cee'd
Happy Christmas.