I looked on Eibach's site, under their FAQ and this is what it says:
5 What shocks or struts should I use with an Eibach Pro-Kit?
Eibach Pro-Kits are designed to work with original equipment shocks and struts provided they are in good working condition.
13 Does the Eibach Pro-Kit work with the OEM shock?
All Eibach Pro-Kits are engineered to perform in harmony with the original damper of the special vehicle - take for granted a good working condition. All TÜV approvals in Germany certify the combination of the Pro-Kit with an OEM shock.
Used to own:2002 Edge 4x4 3.0, 4.10's, 5-Speed Manual, Regular Cab, Oxford White
Used to own: 2004 F-150 STX 2wd 4.6, 3.55's, Auto, Regular cab, Dark Shadow Gray
Now own: 2008 Escape Limited 4wd Loaded w/ eveything. 3.0 Duratec, Tungsten