40mm drop with 18" alloys

[RadRup]

Hi all, this is my very first post, after owning an A6 2.8Q sport for a few years, I've just moved on to a A4 1.8t cvt ( amazing car!! ) I've just put on some RS4 18" alloys and it looks like i'm riding on stilts, so i'm contemplating droping it with lowering springs, i was looking at 35mm but I can only get a 40mm kit at the mo. Has anyone had any experience with this kind of drop, in terms of ride quality, rubbing etc etc. any input will be hugely appreciated.
thanks guys...and girls :)