Unless you've got a HUGE sub enclosure, you could fabricate a homebrew box that fits down on the floor pan betwixt the rear seat and the front seat. The bass really gets your attention there, even with the tiny 6.5" JBLs I use. Leg room is not an option in a Contique, anyway, and besides that my kid is still few years away from 'adulthood'.
Damn that adulthood, anyway.
