[Damocell]

Having read this entire thread I'm after some advice if possible although it isn't related to a e9x M3.

I recently bought a Z4 3.0 Coupe which will be used on track and road. It has an open diff at the moment and can brake late into corners on track without upsetting the rear end. Obviously, it isn't as powerful as the M3 with only 265ps and 315nm.

I'd like to be able to steer the car from the rear more but not induce more understeer mid-corner or under-braking

Which would you say would be a better option on track for the ZF unit?
30/60 4 clutch packs
37.5/60 4 clutch packs
30/60 3 clutch packs

Also would you advise a small amount of preload or none at all?

Hope you don't mind the questions, as people have said, this can get confusing.