I have a set of fastways on my 2010 GSA
they are iirc about 10mm lower than standard but you can I think get bits to lower them a touch more
these and a set of ROX risers works for me
Wunderlich do a set that will lower by 25mm, though if you use their rubbers you lose a bit of that. The BMW ones for the LC can be made to fit and have three height settings.
I have a set of fastways on my 2010 GSA
they are iirc about 10mm lower than standard but you can I think get bits to lower them a touch more
these and a set of ROX risers works for me