Solution for audio system in model A?

[bettlesr]

I have the Subaru sub woofer under the front seat in my Sport Coupe. It's about 9 x 12 x 2". The speaker is a metal cone about 6" in diameter. There is a gain control as well as crossover frequency adjustment. It adds a nice thump to the low end. It turns on when a signal comes into the input. I have attached a picture of the same unit in my Lotus Elan, also under the drivers seat.