Thanks for the input. I must admit that I am coming round to the idea of a plate diff, as the car runs less than 400bhp (currenlty about 350 ish), but on the track, I worry that the ATB might be a bit vague.

I will look into the ZF and gripper a little more.

rabmc - what is the diff like at breakaway? And does it change the reaction on the pick up?

Cheers

JJ