I'm using yellow konis with eibach springs.
The car became much more stable but the ride is uncomfortable especialy with 45 profile tires.
I would recommend those with a softer spring like H+R or Apex.
Bilstein black and KYB excelG are OEM shocks for the K11 which are not intended for lowering.
If you can afford it go for custom coilovers with narrow springs at your local suspension specialist.Avoid those made in Taiwan(D2,Ksport,Daiyama etc).
Finaly Avo and Bilstein make top quality adjustable competition coilovers for the K11