OP, how much of your trunk are you willing to sacrifice for your box(es). If the GP in your pic is your car that is A LOT of trunk space (i have an 04 GP) i would think someone like Moble or one of the other builders here could design you 1 box for 2 subs or 2 separate boxes and still be within the width limits we have at the front most area of the trunk. If i remember correctly we have something like 48" left to right and like 16 bottom to top. only problem is you may have to install the box through the back seats instead of dropping it right in through the trunk.