The spring rate is 8kg front and 6kg in the rear. We have had the shocks revavled by Graham and Mike at Fulcrum Suspension in BRisbane to suit what we do. The car is basically a track car (half caged, stripped weight etc etc).
With the higher spring rate than the super street, on the track we found a few issues with understeer etc. A few swaybar adjustments, shock adjustment and different wheel alignment specs fixed the issued....mind you it took a while for it all to 'come together' again as we were very used to the super street...so it was much a learning curve.
As for what its like on the road....its firm. However with the shock absorbers set towards the softer end of adjustment the drive on the road is quite bearable and the smaller bumps tend to have the harshness taken off it if that makes sense.
If you want to know anything more, just let me know. Happy to help where i can.