Last time I was at Andym's I noticed he still had the custom sub he had made for his old Smart. It was pretty slim, and packed quite a punch. Even if the box won't fit the speakers sounded pretty good to me.

Brabus also had the cool idea of putting a sub under the seats of the smart firing up, no idea what it sounded like, but I bet it was quite a ride for the ladies

Cheers

Cris.