stereo upgrade

So, as we all know, the stereo's in the Mustangs are less than ideal... Especially the rear fill. My car has the 9 speaker system and its very disappointing, I am curious to know if anyone has added additional speakers (not subs) in the rear passenger area? I will be doing a rear seat delete...

4" to 8" Big Screen Radio conversion for 2019-2021 Mustangs. This is plug-and-play for 2019-2021 Mustangs. Up for sale are all of the parts needed to upgrade your Mustangs 4" screen to 8" touch screen with NAV. After installation the radio is fully functional but you will need a few...