PXLpainter wrote:Wait... so how much room is between the seat back and the front wall of the trunk?
...
Could you fab some kind of way to mount a couple of 10" Subs on either side - eliminating the stock plastic thingy with the little OEM fake paper sub in it? Hmmm...

That's pretty much what I was talking about in my earlier post. The space is not big, and the angles aren't very square. It would be a small box as it was, and you'd have to be VERY good to fit a 10" in there, let alone two.
The reason I went with an upscaled 8" was that it happened to match pretty well with the size of the stock enclosure (around 20 liters), and if it didn't work out, I was going to build a 'custom box' that filled the entire space and used two 8" woofers.
I'm also going to replace the door and dash speakers, add more amps, and disconnect the speakers at the rear seat armrests.
Unfortunately, I get so little time each week to play with stuff like this, that it'll probably take me through the summer to get the sound I want.