This guy has some videos on it.
He has some posts here as well.
There are some other options for flash tuning.
Sounds generally like Stage 1 doesn't add a lot of peak HP (especially on 91 oct), but the butt dyno feels the power.
Stage 2 is going to require intercooler upgrade, sport cat, and think about a charge pipe.
Check the N55 engine section.
https://f87.bimmerpost.com/forums/fo...play.php?f=651