Paul, as Americans say, 'Car look sick'.
When we did not hear from you, I assumed you were fidling with your iphone to see if that would work with this kit
When I fitted M sports retrofit kit, I found my bump stopper (dampers in BMW language
) as bad as yours.
The other difference was M sports rear spring was one coil less and thicker (makred as D3 on springs) compared to SE springs (marked as C1 on springs).
But going on to M sports suspension with RFTs, ride is bumpy on rough roads. I can see non-RFTs coming soon on 19s and later same setup as yours.