Well I can't speak for Will, and I've only driven about 10 miles since, but it's already made a huge difference on my truck.
I did a 93 tune specifically targeted to remedy the 6.2s notorious upshift lag issues.
Since this morning's tune the shifts are much crispier, at better shift points, the transmission doesn't try to keep in highest gear as long as possible ... there is still a tiny lag upshifting through the first three gears, but it was getting less the closer I drove to home, and I'm hoping it will be barely noticeable in due course as the 'learn' mode in my transmission figures out my driving style.
I'm not very technical with this stuff, but if I understood correctly the things that were changed were:
- Shift points
- Shift time
- Deactivate fuel management (4-8cyl)
- Something related to throttle
- Speedo calibration (305/40/22)
- 93 Octane
- General fine tuning about stuff I forget
I also got the Autocal to save my stock tune and for other potential tunes.