From Toby Stephenson:

In low grip/damp astro conditions of earlier this year, I ran the following main differences to the setup you posted:

AE White Spring Front
2 x 1.7mm pistons
37.5wt oil
30K Front Diff Oil
Same Shock mountings/camber/roll bar

AE Green Spring Rear
2 x 1.8mm pistons
30wt oil
20K Rear Diff Oil
2 on Tower, original inside on wishbone
Kit hubs (not the raised ones from 2wd)
Same Wheelbase/roll bar
2mm spacer on inside camber link

I also find that if you are softening the car up to get more grip, raise the ride height a bit to encourage it to roll/lean a bit more.

I prefer to run the slipper a little looser than expected; I just prefer the way the car behaves than with it being tight. But yes, I guess need to be careful not to run too loose so that nothing melts! You can get away with it a bit more when the track is slick.

From Ellis Stafford

Change to the standard rear hubs and lower the diff oils right down. If it still doesn't have enough rear grip put the shocks on the back.