I feel your pain man. I have the same issue, although I have the larger LCD screen and 12 speaker system with subwoofer in the trunk. When driving with the windows down at a decent speed I can barely hear the music, even when cranked.
I checked in at a local audio specialty store recently that does impressive custom systems for cars. As soon as I said I had a 2015 Mustang
they gave me the look of "there isn't much we can do other than replace the entire system."
Because the touch screen includes navigation, climate and entertainment, and because of how the amps are integrated tightly with the speakers, it was going to be a big deal. Basically a new deck would require a new dash panel ($700+ just for that), and I would lose touch screen climate control (no big deal for me). The new deck was going to be $500+ depending on what I wanted. Then speakers and power amps. In the end I figured I would need $2000-$3000 to get a decent replacement system, plus installation cost.
Maybe in a few years some other options will be available, but for now it's really limited.
If you learn of any options let me know! By the way, what part of Canada are you in?
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