So I updated my journal with the new stuff for 2016, but I'll bump this thread too with the audio change I made. I went from the WickedCAS corner sub to a dual 10" rear-firing Zenclosures box. While I do think the corner box is still the best option if you want good bass and to keep the majority of your trunk, the output was lacking for me given how strong my mids and highs were.
I had the Zenclosures unit shipped to me in bare wood and got it wrapped locally in black alcantara with white stitching to match the rest of my interior, with a nice padding underneath. I'm using two JL Audio 10w3v3-4's running in parallel to my HD900 sub channel.
Once I re-did the setup for the new subs on my MS8, the instant I put the first track on I couldn't stop smiling. Finally it sounds like what I've been looking for all along. Clean, tight, and TONS of output. Yes, I sacrificed a lot more of the trunk space as well as added another probably 60lbs, but it was worth it to get the sounds I wanted and if need be it's not too hard to pull the box out.