You are incorrect. The enclosure is, in fact, .92 cubes before sub displacement (which makes it more like .77 cubes with the D9).
Here is the CORRECT way to get NET volume (the only volume that matters) of the enclosure:
You first take the area of the usable airspace:
http://i3.tinypic.com/6p8mpus.png
Then, you multiply that by the height of the enclosure (not counting wood) and you will have volume (Area times another dimension equals volume in case I needed to spell it out).
http://www.google.com/search?source=ig&hl=en&rlz=&q=0.8863*12.5%2F12&btnG=Google+Search
I multiplied by 12.5 since that is the INTERNAL height of the enclosure and then divided by 12 to get back into the cubic feet unit.
That enclosure is NOT the recommended enclosure for the D9 and it will sound like *** with very little low end. I wish people would have more an understanding of what they're doing before buying serious equipment.