Have a look at this thread, have just fitted the H&R 35mm on the A3, took them off two weeks later and fitted the H&R 50mm as the 35mm didn't lower the car at all... not that the 50mm made huge difference.
http://www.audi-sport.net/ubbthreads/showflat.php?Cat=0&Number=356663&an=0&page=0#356663