I have always been of the understanding that you want your woofers to face towards the rear of the trunk, that way you get the whip lash affect of the bass bouncing off the rear and firing back towards the cabin.

I guess you could port the box in the rear and face the woofers towards the cabin to gain the same affect, but I am NOT anywhere near sure on that one. I am just thinking of the general dynamics of how the sound will travel compared between the ways of doing it.

Currently myself I have only a 12" sealed enclosure facing towards the back of the trunk, tucked in under the metal beam that goes across from strut tower to strut tower. I am looking at redoing my setup using 2 10" subs and a smaller ported box for when I install my rear STB and have the port or ports front firing as well.