In mine, it will be firing right into the rear seat, but i have open backed bench seats with plenty of air to be able to move. In your case, you would probably want to remove the metal backing in the seats. Like I said, it isn't a simple install by any stretch.
There is another option where you open up the rear deck and put a 5 sided box with teh open side open to the cabin through the rear deck. But that requires making a grille in the rear deck and still has a box. It also requires the seats to be up to work effectively.
