Hi,
if you do a search on Eibach Pro Kit, then you should get some good info from forum members , myself and WarrenS3 included.....we both had the Pro Kits fitted to our S3's, one 3 door and one Sportback both with very positive results.
Basically, the front is lowered so that the standard negative rake is replaced with a more neutral/flat stance with very little deterioration in ride quality. The advantages are that the way the standard car leans on its front springs when cornering is vastly improved, and the pitching front to rear when accelerating or braking is markedly decreased...all in all, it's a very good improvement with very little deterioration from standard ride quality.
I would definately recommend it..... Hope that helps.