All righty, I swear this is my last bump. Now things are a lot more specific. I'm working with the following:
1) A JBL bp1200.1 amp. It does 1200RMS at 1 and 2ohms, but I'd prefer dual4 or dual1 subs just for the 2ohm load which (I think?) is easier on the electrical.
2) Roughly 4cu of space, possibly a bit more. That's counting a 33Hz port with 48" of port area. So that can be toyed with. Point is I can't throw in something that needs 6cu, nor do I require compactness.
3) No more than $250. So one $250 15 or a pair of $125 12's that can go in a small-ish box are both acceptable.
I know, I've been ALL over the place, but