I definitely would skip Alpine SWS-12 if the goal was to use it in a sealed box. Sealed box qtc is not very good. qtc of almost 1 in a 1cu ft box. 0.9 for 1.5 cu ft box. High qtc affects transient response. The Alpine SWS-10 and SWS-15 have good qtc in a reasonable sized box, but Alpine dropped the ball on the latest SWS-12 IMHO. However, since you're thinking ported, perhaps it would do better in a well designed ported box. If you bump your budget a little, perhaps you could get a couple of Dayton's RSS HO12 subwoofers, which are confirmed for good SQ, sealed or ported box.