They are very similar and offer the same features...All coilover sleeves are similar too...True Coilovers are what they try to imitate and they only do so with their adjustability, not the ride quality...

GroundControl actually tests their setup with different spring rates and keep all that research on hand to help a customer select the proper spring rate to meet a customer's needs...

Eibach makes the coils for GroundControl and you can buy other coils thru GroundControl to change the springrate to suit your needs...

Without a shorter stroke, high dampening strut, ride quality it gonna suffer with any lowering kit...
Zee