I have the same problem. Mine is A8 4.2 Quattro SPORT 1999, which should be 20 mm lower than the standard. The S8 has the same ride height. Rear seems to my eye be too low (or front too high). But I guess the front cannot become higher by itself(?), so I thought that the rear has just dropped since the car is driven 240 000 km.

I tried to fix this with a pair of brand new rear sport springs from Audi, but I got them today installed and the result is pretty much the same, maybe rear is not 1 cm higher. But to my eye the front is too high still (or rear too low).

I would'nt like to invest into a full suspension / spring kit, so all tips are very welcome to get the car nicely levelled!

What to do? I've seen many S8 that seems to be very nice and low, and don't really get why my A8 nose is so high?