I'm not sure what the dealer is telling you that's
normal, the wear or the noise. Assuming the suspension is 'tight' now including good [stock is fine] shocks, any cupping could only be due to a toe problem, which would mean the alignment IS NOT as spec. as you've been told.....Any shop that
offers alignments, should now also provide you with
the 'before' and 'after' settings which will include the factory spec's.....BE ADVISED that BMW and some other manufacturers alignment spec's. are
valid ONLY with the vehicle at a SPECIFIED RIDE
HEIGHT***this means properly ADDING weight to the car or using a pre-loading method that pulls the car down to spec. height before ANY readings or ADJUSTMENTS ARE MADE ! !
As far as noise is concerned, S03's aren't terribly loud [noisy] in my experience having them both on our '98 Z-3 2.8 [17x245 rears] and on our '80 320iS
[15x225].....IF THEY started out fairly quiet, they
wouldn't have gotten noisier over time unless, as
you've stated, it's due to ABNORMAL wear..........jb.