I have the Eibach and Koni's and enjoy them very much.....especially in the last month!!!

Lowering your car will also change your camber to a more negative (inward tilt) and wear the insides of your tires... so you will need a set of adjustable camber arms as the factory camber arms are not adjustable...
in addition your rear sway bar links are a fixed length and will be pressing the sway bar up and limiting the motion of your shocks making the ride stiffer and transmitting more road bumps to your chassis...

Fortunately there is a fix for both of these..... PM or email me....