Installed the T800 UpMap a few days ago, and I'm thoroughly impressed with the difference in throttle response, especially below 3k RPM!
One issue I did have was with my Android and the UpMap application. It was completely unable to 'find' the T800 - the Bluetooth icon would come up, it would go to the 'founded device' screen, and then nothing would happen. The GTM video AND the GM instructions both say it can take awhile, so I left it there while I was doing a few other things on the bike. Even after 15-20 minutes, there was still nothing for me to select. I used my wife's iPhone and it took MAYBE 5s for the device to pop up once the app hit that screen...
My phone is a Google Pixel 6, up to date on firmware, etc, and the app was downloaded within two days of attempting the install. Has anyone else run into this problem? Thankfully, I wasn't planning to mount it permanently to track rides and whatnot, so it's certainly not the end of the world.