I spent a bunch of time messing around with the RB2 manual calibration settings (I don’t have the new Strat), and decided to make a short video explaining them clearly and simply (I hope). I used this method to calibrate my system, and it works really well. So if you’re confused about exactly what the settings do, and which way you need to move them in order to sync up the game, this should explain all of that. I use the drums as an example, but obviously this also works with the guitar.
Let me know if I made any mistakes, and I can add some annotations to the video.
Edit: I originally made this video for RB2, but it also works for Rock Band 3, The Beatles: Rock Band, and Green Day: Rock Band!
Edit 2: a French tutorial has been posted by Stéphane