The Pro-Kit is Eibach's best-selling lowering spring — it drops the centre of gravity, tightens up body control and fills the arches properly, without the compromises that come with a full coilover kit. It's tested to work with the factory dampers, so there's no need to change shocks alongside it.
Technical specification
Lowering: 20 mm front / 5-10 mm rear (M4/M4 Competition); 15 mm front / 5 mm rear (M4 CS)