In my opinion both are stage 1.
I see stage 1 as alteration of the software only, stage 2 I see as stage 1 + airflow (in -and exhaust) and stage 3 with for instance different turbo's eg.
See the link below for their options:
https://www.mosselmanturbo.com/en/bm...-g11-g12-450hp
So their Itronic module is basically a plug and play tuning box. They say that BMW can't trace it in case of warrenty issues. But then my contact in BMW say they can see everything. I am not an expert so I don't know.
Why I went for the remap and not for the Itronic is that with the remap the Vmax is increased. That was my secondary wish after the power increase.
As the car is still under full warrenty the next 1,5 year I am taking a risk now with the remap.
My previous F10 535d also had a Mosselman remap. Never had issues with that.
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Current: MY18 G11 750i (daily), MY14 Porsche 991 S (x51, m/7) (fun), MY17 Mini Clubman JCW All4 (GF)
Retired: MY14 F10 535d, MY11 F11 530d (temp), MY10 F10 535i, MY87 BMW E30 325i (fun), MY74 BMW E3 2500 (fun) (and more..)