So I'm thinking of adding an amp and some small-ish subwoofers in the back.. there's a good amount of space for some shallow 8's maybe. Here's some photos from taking out the passenger side back panel.
To take the bottom seat out, just unbolt the front and push down on the back of the seat while pulling the seat forward.. there's a small clip in the back. To take off the panel, there's a few clips to take off in the trunk nearest the back seat, then partially pop out the side plastic on the bottom rear door frame.
Next, pop out the clip towards the back of the now removed seat. Now pull the panel towards the drivers side from the bottom left. The panel is held on by about 7 clips.. pull until it gives some resistance, then pull quick to pop the bottom left one out. As you pull the others out, use force from close to the clip so you don't bend the panel too much (it will have some pliability though).
When they're all out, you can move the seat belt out of the way and gently nudge the panel forward towards the front of the car and pull it through the passenger or driver door.
It worked for me
Mike