back of a blazer should have much more than 6-8 cubes //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gifi was thinking of getting the sub or subs first and then build the box and pick up a amp to push it all,as far as cube feet i have about 6-8 cubed feet to work with in the back of my blazer