The power output is near enough the same from both tuners, i have been running stage 1 on my car for over a year with no problems.
Stage 2 is just amazing, the car drives as stock till you plant you foot and then all hell breaks loose.
Evolve is continuously improving their maps as the are currently working on a 1M project.
They are planning a twin turbo replacement for the N54 with a estimated 550hp