I want to say that the koni's from GS will lower the car about 1.5" or 43mm or something close to that. Ive been looking into a new suspension setup myself.
http://photo.platonoff.com/Auto/20070511.Saab_NG900_Eibach_Springs_From_a_9-3/
http://photo.platonoff.com/Auto/20070511.Saab_NG900_Eibach_Springs_From_a_9-3/