...I'm trying to gauge the unsprung weight savings under the various alternatives.

There may be lighter, aftermarket versions available, though.

I asked about direct replacement aftermarket S4 rotors a little while ago, but basically got no where. I want to do a BIRA staqe 2, but with lighter aftermarket slotted rotors. Tonight I was looking on MC's new site and see that he offers stock-sized S4 rotors from Alcon with Pagid pads for $1495. This seems awfully high, though. I had called KVR Performance about a week ago and they said that they would make S4 sized rotors w/aluminum hats for $395/rotor. They did not give a weight since these would be a custom size for them. I was told that Tarox makes a rotor that would work as well, but I have not found out for sure yet. My first choice is the Tarox rotors with Porche 996 calipers. I have no idea what this would weigh, but I would assume that the Tarox would have to be less than the stock S4 rotors.

I got that from Camra Motorsports (link on AudiWorld links page), but best to call and talk to Andrew, whose e-mail is camra@sprintmail.net.

A nice write-up of the install can be seen at audizone.com.<ul><li><a href="http://audizone.com/info/apbrakes/apbrakes.htm">AP Racing Brake Upgrade</a></li></ul>