I have never posted before, but I have used everyone's amazing DIY posts over the years.
raise:
I could not get the E90 head rest to tilt like my E46. The headrest did not tuck in comfortably at maximum tilt.
After an intervention the difference can be seen now between right head rest tilt (DIY) and left head rest (original):
step1: remove headrest.
step2: drill part of the plastic restriction away (try not damage leather/fabric).
step 3: use utility knife to cut off excess plastic (try not damage leather/fabric). I used a too large knife, but it was strong to take large excess off, then I used a smaller utility knife to clean up rough edges, so that the headrest could tilt without 'grabbing'.
I could not get the E90 head rest to tilt like my E46. The headrest did not tuck in comfortably at maximum tilt.
After an intervention the difference can be seen now between right head rest tilt (DIY) and left head rest (original):

step1: remove headrest.
step2: drill part of the plastic restriction away (try not damage leather/fabric).
step 3: use utility knife to cut off excess plastic (try not damage leather/fabric). I used a too large knife, but it was strong to take large excess off, then I used a smaller utility knife to clean up rough edges, so that the headrest could tilt without 'grabbing'.




