vented box

I'm planning on putting two 12's on my 2007 Ford Mustang Convertible. I've been looking into the 12" SSA DCON 12D4/S4 or if not, then the Street Duty SDC2.5-12-D4 Subwoofer. I don't know which one to go with or wether or not to seal the box or to port them. Any help would be great. Thanks.

Loud, accurate, and full of good ideas.