I found that the trunk is big enough for a nice large braced ported inclosure that will fit 2 11"s in it. You can brace the box between the floor and the rear deck and keep it nice and tight. You can see how they fit at my sound domain page here.
http://www.sounddomain.com/member_pages/view_page.pl?page_id=252155&page=2
We filled the boxes with deflex pads and its really nice and tight.
http://www.sounddomain.com/member_pages/view_page.pl?page_id=252155&page=2
We filled the boxes with deflex pads and its really nice and tight.