As the originator of this thread, I thought I would follow up at the 9 month mark with my current solution. I did a lot of research. I didn't want six inchers, no way no how. I didn't want shallow mounts either- they just can't take the pounding I wish to inflict upon my sound system. I ended up going with a Rockford Fosgate P2 10 inch sub in a sealed box that sits on the middle of the back seat. I can still seat two grown men on either side with room to buckle in. The box cost all of $50 at Circuit city, and is 11" x 12" x 15" and the sub fires upward. It sounds AWESOME! Hits real deep, and tight. I never would have went with sixers in the first place if I knew. Total cost was less than $200.