There was a group buy a couple of years ago on
http://www.a8-freunde.com/
you could ask on there they probably still have the details.
I believe they went for Goodridge ones, but may have had them specially made for the group buy, I cant see S8 or A8 on the Goodridge website.
http://goodridge.brakes-hoses-fittin...r-brake-lines/
This place still has the A8 kit, not sure if it will fit the S8 too...
http://www.ccc-motorsport.de/shop/19...%C3%BCv-detail