@Fschorsch
It depends like always on your budget.
For the BMW M3 we developed the KW HAS, the KW V3, KW V4, KW CS, KW DDC plug&play.
If your M3 is already equipped with adaptive BMW Shocks you should think about the KW DDC plug&play kit. With the DDC you still can switch by push of a button between the different suspension modes.
If you want ride your M3 mainly on race tracks upgrade to KW Clubsport.
Front Street provided us with an cool installation feature in a M3:
http://blog-int.kwautomotive.net/bmw...a-closer-look/