Very nice!! And I know exactly what you mean, I bought a new A4 BE last year and straight away wanted to lower it to a more sporty stance (to look like it should from factory, not slammed or anything) and it took calling around 5 places before someone would even consider installing the springs. None of them wanted to touch it being so new, and said that they didn't want to get in trouble if something went wrong and I needed to claim for something under Audi's warranty. Ridiculous, but managed to find an Audi specialist just around the corner from me who did it and it completely transformed the look of the car. So anxious to have the same done on the A5, earliest I could book it was next Friday.
Well having done a great deal of researching on spacers for the A5, with the standard 19" wheels you could go as wide as 20FR/25R without scrubbing. Most tend to prefer the look of the 25R however it's really borderline for me, people disagree whether it protrudes from the arch or not which to me looks too much. That being said, I haven't seen a single person mention scrubbing at those widths, all lowered (most on H&R OE Sports which are pretty low). A lot of people tend to go for the 15FR/20R as its the safest compromise between getting the stance and not worrying about protruding beyond the arch. It sits just inside the arch, and looks great IMO. I may start with 20mm at the back, and then add the 15's at the front later.