I heard another fellas Shaker 500 after he replaced the door speakers only and it sounded much cleaner and clearer. not sure how much difference replacing the rears would make, I have a small amount of fade to the rear just for fill. he used Polk Audio db571's so I bought a set of 4 and never got around to installing them...
I bet they would have sounded just fine.
2011 V6 Premium ,Grabber Blue/White Stripes/Charcoal Black, Auto/2.73, 202A Pony Package, Comfort Package.
Mods, Factory Engine Cover, Ford Strut Tower Brace, 19" Painted Aluminum Wheels/245-45-19 P-Zeros, Wheel Locks, Ford Accessory Alarm, Ford All-Weather Mats, window tint, spare tire/jack, cam cap mod.
on deck... Polk Audio db571 X 4 speakers & baffles