Looking for some input on rear speakers to replace stock for rear fill. I run a front stage but just want to fill the void.

 

I went with a set of Diamond D6 Coaxes. Really, find a nice set for under $150, and you'll be fine. You definitely want to upgrade the rears if you do everything else so you have a more balanced system that isnt completely lacking in the rear, albeit the rear isn't of utmost concern