Cathleen

Here's another option on coilovers if you want something that was designed and tuned specifically for the most optimal ride performance on the A4.
Yes, I am biased since my car is a project car tuned by Vortrag and I'm an investor in the company. However, I am a driving enthusiast first and foremost and I saved my own money to get these coilovers (yes, I still have to buy my own stuff).
I've driven all different makes and brands of shocks and springs. We've had experiences with everything Koni, Bilstein shocks, Neuspeed, A!AvantGarde, Eibach, H&R springs and so on.
As far as springs, we use Hypercoil springs now. Hyperco (who makes Hypercoil springs) is one of the top spring producers to CART and F1. These springs are a top class product and they last.
You mention drop, but what's even more important is being able balance the vehicle's weight distribution (50/50) for incredible handling.
I just had the Vortrag Coilovers (Custom-valved Koni/Hypercoil race springs) installed before The Quattro Club Nationals at Road America.
This coilover package is a slightly more expensive setup than the other packages out there, but it is with no doubt the best I've ever driven. I can tell you that my car was phenomenal on the track at Road America this week. I was blasting through the water and the miserable track conditions with the most stable, flat, precision ride I've ever experienced. I was just plain FAST. The car drives like it's on rails! Total predictability. It is not harsh, either. My stock Porsche 944 is wayyyy more harsh than this and does not drive even close to as well as this. My springs are at a very high rate...because I am an aggressive track driver. Still, the ride is very comfortable to me. I have to drive this car every day to work (70 mile round trip) and on Michigan's pot-hole ridden streets.
People think that a track setup won't be acceptable on the street. It's all in how the package is combined and matched. You have to have the right valving and properly matched to the spring rates. Also, the spring can make a big difference in time. My Konis and another set of our H&R's went soft after a year. They were great at first but gradually, the body roll became worse and worse with time and then the shocks had to do most of the work. It went from a comfortable ride to a hardh and rolly ride.
The cool thing about the Vortrag Coilover-Koni/Hypercoil setup is that they have a lifetime parts warranty, so if the parts ever have a problem, they are replaced. There's a spring exchange warranty too. So if you go with spring rates you think are what you want, and find they are either too stiff or too soft for your liking, Vortrag will exhange them for you free of charge.
As I said, I'm really a driving enthusiast first. That is why I got involved with this whole tuning thing in the first place. What I liked is that Vortrag's main focus is to build the absolute best product out there. Not just for everyone else, but because they wanted the best stuff for their very own cars.
-Cathleen
---Computer leasing by day, playing with Cars n' Toys in my free time ;-)

Cathleen

P.S.- that' was my "Eibach springs" went soft, not my Konis (typo).