I ran my cyclone on the weekend, the Pro4 diff seemed to help on the corner exiting, I could accelerate alot faster out of corners without the rear end stepping out. I think there was something wrong with my cyclone diff.
As far as setup goes, I didn't change anything from my posted setup plus the silver front springs and the 2.5 degree toe block. My laptimes were withing 1/10th of the usual fast guys who were faster than me down the straight but the car still seems to have alot of understeer. But I have a feeling that is due to the lack of grip on the track surface.