Hey Lin,
This topic interests me. What do you think about kick panels?
Hi Levi,
Cars are so different that I have heard all speaker locations sound good and bad.
Are you happy with the way it images and sounds? That is all that matters.
I have a friend that is a dealer/installer, in one of his vehicles he has tried all kinds of drivers in all possible locations (including custom) and he can not get satisfying sound, in his other vehicle he puts decent drivers in the stock location and it images and sounds great.

I agree that the rear speakers are for rear passengers only. I want to try wiring the rear in series.
Are you using an outboard amp for the rear speakers?
Is it bridgeable?
If yes to both questions try bridging the rear channels to mono and series wire the rear speakers to the mono channel.
This is most effective with rear deck speakers since the rear speakers have a fairly direct path to your ears.
I've heard cars that the sound stage from left to right goes like this:
LF LF LF LR LR CF CF RR RR RF RF RF
A front faded setup and mono rear signal tends to cure this since all the rear sound seems to come from the center before it starts bouncing around.
Lin