You need to carefully consider how much you want to spend, and what affect the lowering will have on the handling.
If you lower the car excessively (and some of those images above seem to be verging on that) you start to encounter problems. The A4 has a pretty decent suspension setup, so the geometry issues arent as pronounced as they would be on a car with Mac Struts, however, if you lower it too much, the one big issue is that you'll run out of travel on the shocks, meaning you'll bottom them out under certain circumstances (or all the time if you go too extreme).
The last thing you want when you hit a pot hole half way round a corner when your driving a little to fast, is the suspension to bottom out, as once that happens, all the control over the wheels contact with the road disappears, along with the control of the car, as you head towards the hedge...
The other thing to take into consideration is budget. If your wanting to spend say £400, you'll get a much better end result fitting a set of Eibach springs and Bilstein B6's than you will fitting a £400 set of coilovers. I'd say that unless your prepared to spend 700-800quid or more on something like the PSS9's or KW V1/2's as the other folk in this thread have, then forget coilovers and fit an Eibach Pro-kit and a set of Bilstein B6 shocks.
could you guys post pics up of yours with wheel size,how much your car is lowered and what suspensiion setup you are running 
, didnt notice that!!! Power to the Bubs 
