Knowing almost nothing about building sub boxes I decided to cut the existing one down so I can actually use the trunk. I have long found it embarrassing to open the trunk and only have a sliver (literally only about 12" of trunk along the back not filled with enclosure). It was really brought to my attention recently when I picked up some people from the airport and two reasonable sized suitcases couldn't fit back there.
I took the existing box and cut 10" off the back of it and replaced the back cover on the now much smaller enclosure. I also moved the port to the back of the box, and replaced what I would consider ittshay wiring inside the Kicker factory box.
Sound wise I am ok with it. It certainly doesn't seem to punch as hard as it used to, but to my ear it's more reasonable sounding from the two 10" subs. The better half will give the final ok though, as she's the one looking for bass that punches you in the gut. No pictures of it yet as I have to make it pretty again, but after some tests, I'll determine if I'm keeping it this way.