[from the archives at http://archive.grassrootsmotorsports.com/board/viewtopic.php?id=27160]
My experience with S2000s is all on track, not autocross. I'm not an S2000 expert but I have first-hand, left seat experience at the limit. I like S2000s and think they are fantastic track cars. I'm not bashing.
The early cars had an issue with rear toe control. Under deflection (hard cornering) the outside rear wheel would develop dynamic toe out. What this means is that as you are, for example, turning left, the right rear wheel, as it becomes fully loaded, starts to turn RIGHT and you get a possible oversteer situation.
Note I said a POSSIBLE oversteer situation. The car doesn't just spin itself and it's not an uncontrollable thing. However, and to me this is key, what you have is a car that does not behave in a linear fashion. What do I mean? As you add steering, and cornering forces build, the car rotates at a certain rate. However, as you reach that certain point on the suspension travel, increased steering causes rotation to increase AT AN INCREASING RATE. With the S2000 rear toe control problem you get a very spooky feeling as you approach the limits such that the car starts to over-rotate and you think the rear end is losing traction but it is in fact the change in toe increasing the rotation. Both the owner and I found it very spooky (each drove and reported the same thing, and we're both experienced drivers). This is the same issue found on first generation RX-7s, which also have a reputation for snap oversteer (and I have extensively driven those on-track, as well). To drive a car at the limit it needs to be predictable, and linear is predictable and non-linear is less predictable.
Since this experience was at high speed on track, would this be an issue autocrossing? I say yes, for any serious driving. When autocrossing you need to be able to very quickly, accurately and consistently push the car right to the limit of rotation and an unpredictable (non-linear) response will hinder that.
OK, that's the issue. The good news is that there is a simple fix out there. It's a rear toe control kit and, if I recall correctly from my friend, it sells for less than $250 and is an easy install. The same car in the same turn was transformed from a white-knuckle "I don't dare go 10/10ths" to "Yeah baby yeah baby push it!"
I respect Honda's engineers a lot and I theorize the S2000 was their baby, so I'll confess I'm a little shocked Honda let this slip by.
[edit] I've since driven other early s2000s on other tracks and confirmed the toe control issue. The model year 2000 I just drove was even worse than I remember, but then the rear suspension bushings are now eight years old and probably allowing even more toe change.
I understand the toe-control issue was present from the car's inception. I think it was solved by the factory when they revised the rear suspension, which I think was in 2002. I'm not a S2000 timeline expert so please research further. I can't tell you the manufacturer of my friend's kit, but I'm guessing you'll find several solutions online.
Now if only there were a simple, cheap, easy-to-install solution for the poor steering feel...
Good luck!