I guess dissconnect the steering angle sensor? abs uses just the brakes and wheel sensors, ASR / ESP uses above, plus steering angle...
or have a lookk on here:-
You're probably right. I knew that 'off' didn't really mean 'completely off' but I assumed you'd get more scope for hooliganism that way! Maybe not enough though ...
I've never switched ASR off on mine, I get a small amount of wheelspin even with it active (I guess till it spots it and reacts).