How low can i lower this without the need of having camber issues?

im thinking of going for 18'' rs6 style wheels,depending on how the car looks (if it looks ok then il leave it on standard sport suspension)

I may want to lower it but want no issues with camber or any other issues.

Thinking of getting eibach or apex springs (i want same drop all round)

any pictures of a sport (with standard sport suspension) fitted with 18'' wheels would be of great help.