I was quoted £350 to supply and fit to my 2018 Mazda 6 last week. I won’t be taking that offer up. Apparently they upgrade the USB port(s) as well to charge at 2.1amps to support devices with larger batteries (don’t know if that’s one or both though). This should charge an iPad whereas the standard port won’t.
The £350 price covers updating the firmware to v70, the new USB ports, new cables, and the fitting. As part of this, the main (#1) USB port charges at 2.1A yes - useful as the standard port barely charges my iPhone 6S currently. I'm sure the newer and large phones would struggle even more.
I decided to go for it and ordered the parts last weekend. They're already in stock so I need to go and collect them. When time allows, I'll fit them myself. Will update here in due course.