Subs:
Alpine swx-1243D subs
Amps:
Alpine mrp-m1000 for each sub because the subs are just that good
Box:
I'd go with Alpine all day, and dual sealed box just for better sound quality, but for this system it probably wouldn't matter. Preferably custom. I don't know about internal volume and all that. You'll do better to ask a professional about that.
This system brand new would cost an arm and a leg but you can find a decent deal on ebay for both the alpine amps and sub
The cost, however, will be well worth it.