"As for leaving the rears, I wouldn't recommend that"
Upgrade the rears ONLY if you tend to watch concert by looking at the rear of the stadium.
Rear fill is meant to be just that REAR FILL! 85-90% of the sound should come from the front speakers.
You basically need to take the entitr rear dash, and one half of the rear seat off to get at it.
The deck shoulf be pretty easy. You should have a spot where the "accessory" socket is plugged in. If I remember, that just pulls out and there are 2 bolts under the dash, 7-8MM I think. Unscrew them and find a spot to push from behind it should just pop out..
Try this link, sorry about the other one
install
Brent