Found this picture now I’m curious…..is this a good position for rear fill (not the angle in the picture) but the placement. I’m not concerned about the little window because I don’t use it anyway. Seems like a better speaker position rather than the speaker firing at your back. Experts please chime in.

 

zero point.. the sonic difference is null.
Path length difference is probably still close to the same.

I promise you that it would "look cool" but offer no improvement. .

run in the factory spot and attenuate them almost all the way out. Spend ur cash up front in the doors.

 

^ This, here's the deal. Get a nice 4 channel (Bridge it) or 2 channel amp, run the fronts off that. Then run the rears off the head unit, this is what I'm doing and trust me get some decent rears but you're better off spending more of the money on the fronts.