700/800. Same rates as were on my Tracksport setup.

You had the tracksports on the avant?
 

I ended up going with 725/900 with the 22mm H-sport sway. The car really likes to turn now :)

As far as the A4 Stoptechs and Alcons, I would say that they STs feel on/off with limited
 

modulation on the street. However, once I get some heat into a track pad at the track, I definitely have more modulation at the bottom of the pedal in heavy braking zones.

After driving a friend's A4 with Alcons on the street, the first thing I noticed was how linear the stopping power was compared to my STs.

But, for a $2k kit (STs), it's a helva lot more brakes than OEM and I've only experienced pad fade on the street and fluid boiling on the track using Motul RBF 600 and Pagid Orange pads - which never faded. I got about 9 track days out of those pads, fwiw.

Are those 18" OZ's in the picture?

Yes.

Yessir. I did.

Why the upgrade? Not happy with the tacksports?
 

I decided to go with the OHLINS after riding in Zev's car. The tracksports are a great suspension but seem bouncy in certain conditions which the OHLINS do not. And the adjustability on the MS setup is NICE! Very easy to get things dialed in.

rears stock?

Well...
 

The Tracksports are nice, but since I don't choose to afford myself the luxury of a dedicated track car, I needed something that could be "The Best of Both Worlds". As a single adult male who is supposed to be a "grown up" it was a little difficult explaining to women why my supercar rode the way it did with the TS kit. To me, it was quite acceptable, and even enjoyable, except on drives where I was not familiar with the asphalt terrain. The Mo'Sport stuff is amazing in its ability to be both absolutely better than stock comfortable, and also the best available in terms of demanding performance all at the same time.

Worth every penny!

Why do people associate rotor size with level of braking?
 

Rotor diameter has a small affect on overall brake bias, but what it IS useful for is efficiency. The larger the disc, the more efficient it is at cooling, which is it's job.

Pads have a far greater affect on bias.

Rotor efficiency improves with diameter. And given the weight of the S4, the increased efficiency of the larger disc is a nice advantage. Having more efficient brakes does not make them "overkill". Yes, you can go to far and have rotors that never heat up, but in the S4, in a 19" or smaller wheel, this isn't going to happen. (IMO...)

Here is a picture of a rotor to increase post views...
<img src="http://pictureposter.audiworld.com/4359/252_vented_disc.jpg">