Loads of people and loads of posts on this one available via the search function.
Norm for the S3 is usually 10mm front and 15mm rear.
Damian @ DPM
if you stick to a 25-30mm drop you shouldnt have any problems
most go for the h+r springs and billy shocks i have the h+r springs and roll bars and there great, also depends on the off set of the wheels more than anything, i have 8.5 * 18's with a 35mm offset with 25mm rears and 10m front spacers and the wheels now fill the arches all the wayAh cool, thanks pal - was thinking of Eibach springs but yet to decide on shocks...
oh and it is an s3??? as a3 has not got wide arches
most go for the h+r springs and billy shocks i have the h+r springs and roll bars and there great, also depends on the off set of the wheels more than anything, i have 8.5 * 18's with a 35mm offset with 25mm rears and 10m front spacers and the wheels now fill the arches all the way