GMC/CHEVY crew cab- limited space-what's the most subs installed?

Hi, I have an 05 GMC Sierra crew cab and was wondering what is the most subs that you may have seen or done in these trucks in the limited amount of room that they have... no blow thru's and back seat still in.

I have only seen (4) 8's under the seat, facing forward, or (2) 10's or 12's firing either up or down under the seat.

What champ said, and don't forget about the center console box. I'm not a fan of firing up into the seat. I'd take 4 8's firing forward instead.

I, have been looking around on the net, YouTube, other forums just trying to who has gotten the most creative and haven't found much. Just like the two of you stated with the 4-8s or 2-10s. I really didn't want my truck sounding like garbage, being limited to prefab hell.
I was having one of those days where I was really motivated so I pulled my back and redrilled my seat brackets and got my rear seat moved foward 2". This alone opened up a whole new world on possible sub options... but that wasn't enough. I cut out the stiffening plate under the rear glass...by the way offered nothing when I came to stiffening up anything as it was not much thicker than a soda can. At the base of both plastic interior panels to get the most room for my enclosure.
I started pulling a tape and getting my numbers ... I ended up building my box for 2 -Kicker CVR 15" sharing 4.92 cubes. I have them on a JL 1000/1 with a 140 amp alt and two 950ca batteries (mounted under the hood) I gotta tell you it as nasty as can be. It impressed me on every level. They really do sound so good to the ear and hitting ever note that's wanted. The flex on the truck is something to see as well.
Not trying to come off as bragging or anything ... just wanting to share with whoever is stuck in the crew cab limited audio zone..Attachment 5557

Sounds great !