seat but you can't tell and nobody has ever sat back there. 1/2 is under the seat, 1/2 is back. I could fit it all under but I like to move that pass seat forward/backward and I think the xtra space gives it some breath.
It was a 4 channel so I'm running 2 to the fronts and 2 to the sub and it sounds incredible.
Good luck with the install. Post pics when done. Thanks for the advice on that job, it wasn't really that hard!