Couple issues with Torsen diffs on the track.
1) It works under power differently than off power
- When you use your throttle to steer, or lift a little in a corner, the car could get a little unsettled as the torque redistributes. (Though it does adjust much faster than a viscous or clutch based LSD)
2) Requires both wheels to have traction
- stiffly sprung race car can easily lift a wheel at apex as you run over bumps/curb, making it hard to put power down.
They work great as a center diff or a front diff where it's more open-like behavior is critical for control.