My cars chassis has been fettled by Birds BMW here in the UK.
I used H&R springs as I wanted to retain adaptive dampers for the time being as Birds had not yet developed their B1 spring/dampers yet.
I got the B1 package # 1 as noted in the link below.
http://www.birdsauto.com/tuning/sear...mi=M135i&pg=10
They do a B2 package #1 and # 2 for M235i
http://www.birdsauto.com/tuning/sear...mi=M235i&pg=10
Heres 2 write ups about their B4 chassis package their do for 3/4 series, which includes sway bars
http://www.pistonheads.com/news/ph-d...i-review/30963
http://www.birdsauto.com/editorial/e...tions-sep-2014