soundqubed hds215

So, I bought two hds215's, and the recommended is 9 cubes. I'm looking for loud and low. My Honda has a trunk with 31d" 33w" and a height of 17". I'm also wanting to port the box through my ski pass, which is 7 1/2" by 12" but I can cut it out to be a little bigger if needed. I have 9 cubes...