FYI, if the measurements are correct on Sonicelectronix, I don't think that sub will fit under the seat.
I don't think that something 6" tall will fit under the seat in my 2011. I just measured my passenger side quickly and I don't think anything taller than 4 or 4 1/4 inches will fit. I have my driver's side most of the way down so I don't think I would get much more clearance there.
And the 19" depth would have it taking a lot of the floor in the backseat.