That's exactly what my current setup is and exactly what I'd love to have instead. $2k is a bit steep. Were you able to resell any of your old stuff? Where are you located?Just wanted to outline another successful install on a 2015 NA GTI.
Stock was Fender MIB1 with NO navigation but I did have CarNet. Upgraded to an 8 inch screen, MIB2 and USB socket and kept the existing MIB1 amp. All hardware was ordered from APG in Poland, they were easy to work with and everything arrived in the US within less than 2 weeks after order.
Hardware install went smoothly, thanks to the guidance from paul_elstak's original post and the follow up posts from JWadle and dubpar. Also appreciate dubpar helping me validate a few install items via PM. All and all these posts and the advice received were spot on for installation. This is coming from someone who was very nervous about digging into their dashboard and with little experience with installs like this (I only did one similar before swapping an RCD 510 for and RNS 315 on a MKVI).
I just took my time and validated each step before executing and didn't rush. The most difficult (and nervous) part of the whole hardware install for me was getting the trim around the display unit off. Some of those clips are persistent. Other than that, it was really straightforward. Even the cable fishing for the USB wasn't too bad, a good flashlight and sighting where it was supposed to go helped a lot for me, plus I think I got lucky.
That said, on the software side, I did have one issue where initially everything seemed to be working on the display, but I had no sound... APG was very good about working with me on troubleshooting using VCDS scans and it only took a day to get it sorted just because of the time difference and our mutual availability. They offered to Skype or direct message with me to troubleshoot, but scan reviews solved the problem. Ultimately, it turned out to be a single byte change that was required and the sound kicked in. Of note, the tone controls now indicate Dynaudio now but seems to have the same features as the original Fender tone controls and it sounds good.
I also had an issue with the USB port initially and my iPhone. It would charge my phone, but not recognize the iPhone as a device. Turned out to be the USB to Lightning cable. When they say use an Apple cable, they really mean an Apple cable, Apple Certified did not work for me.
One last note, I did have CarNet as part of the stock setup, there was some debate on whether I needed a GPS antenna or not as CarNet has GPS for tracking even if you don't have a Nav system. I had an antenna ready, but when I pulled the MIB1 there was an antenna plugged into the back and it reached the plug in the new unit fine so I decided to try it out and it worked. So I was able to use the already installed GPS antenna even though I didn't have Nav originally in the car.
Hope this helps anyone contemplating the upgrade. Similar to other posters, I was in it for a touch over $2k and its well worth it to me. The new CarPlay and latent Nav features are fantastic, and the interface has cleaner resolution and is snappier to respond and everything is OEM and works like it should. I was looking for certified used options when we picked up this car as I wanted a 2 door before they vanished in the US, but we wanted CarPlay and Nav. Finding a 2016 2 door with the features we wanted was impossible. The price difference of going 2015 with low miles helped justify the upgrade to what is essentially 2016 specs+ (due to 8 inch screen) for the audio system.