The LSD on the 6-speed boxes was a £100 option. I specced it on mine ( although you could get it as part of the Chilli Pack )

Strictly speaking it's a torque apportioning diff like a Torsen or Quaife diff rather than a VC or plate LS diff.

It's the GKN Super LSD and is also used in the Mazda 3 MPS.

The bias ratio isn't particularly savage, it's roughly about 2/2.1