Are the subs accessed from behind the bulkhead or in front of it?

I have been wanting to add some bass sound to the car but there is such little room in there that I do not see a solution. Been wondering what others have done to remedy this problem. Putting a compact sub box between the passenger seat and the rear bulkhead is all I can think of. I was told by a professional stereo installer that a compact sub box will not fit under the seats.

Not meaning to pirate the thread because I think the OP might find a solution as well with my questions....I hope.