how about 3 in ported boxes, i'm running 3 12" lanzars in a double ported box and a single 1.2 cu box and bass is beautiful and i have enough space for an overnight bag in the corner of the boot of my a6 /ubbthreads/images/graemlins/lol.gif
i used boss 4000 amp as a quick solution for them and i can honestly say it has not missed a beat over the last year using a second battery in the 'boot' (or 'trunk' as you say in usa, i'm a brit) no need to change amps its strong as an ox and putting out near 150 db at full tilt which is enough even on occassion