I totally forgot about your build. Looking good! Do you more pics in your build thread? If so, I'll have to go check it out.
As far as my sub, it's just going in the stock location in the rear deck. If I have the need for more (probably will), I'll do something like what you've done with a pair of 12s or 15s. I'll be getting a big enough sub amp to power pretty much anything I want.