Ideas for 99 QX4

I have a 99 Infiniti QX4, and I decided a while back I was going to trick it out for show. So far I did a new paint job, 5 coats of metallic silver, 20" Giovannis, and front chrome grill, tints. Now i am thinking about the Audio System.

I am thinking of putting 4 12" momo subs in the back. Anyone have any suggestions for me?

Put two subs on each side in the back, put the amps in the middle on the floor, and possibly a monitor in the middle near the back of the seats. Just throwing a idea out there.