Jason,
slight topic hi jack but I tracked the S4 at the Nurburgring recently and was a touch dissapointed. Huge straight line speed but lack of high speed stability.
I did a session on the grand prix track too, and managed to spin it! Luckily lots of run off there.
There is zero understeer and lots of gripo just a lack of control - the car felt too soft. I think this is mainly due to the Eibach pro street being too soft. Looking at some PSS9's or AST's to replace them with, what do you think?
Rick
Oops, sorry I missed this. I think it's an alignment issue. You probably need more toe in.
1) toe OUT makes the car turn in very sharply, but makes the car unstable at speed. Short tracks and autocrossing are good for 0 toe or toe out.x
2) toe IN makes the car turn in very soft, but makes the car stable at speed. This is better for long tracks and highways where the car tramlines.
Does the high speed stability get worse as you brake? How much caster are you running? Do you have adjustable upper control arms?
If the car stays reasonably flat, doesn't understeer during transitions (direction changes via steering input), I'd say leave it alone and add some toe in. Too much toe in and it will feel boring. Not enough and the car will dart around.