Our car is being built for autocross, so any recommendations you see here may not be applicable to the street or track. Our car is street legal for convenience, but is being build for performance not street comfort.
The new Hypercoils are installed on all four corners. Wayne, we went with your suggestion and we are going to try 450F/500R tomorrow. Seems like it is popular with the lotus crowd (in autocross) to run even stiffer rear springs (more like 800 rear), but with us coming from Miatas (which run closer to 700+f and 400R), it's a little hard for us to be willing to jump that far yet.
We don't like a loose car. Is there a reason that many of the mid engine cars run so much stiffer rear springs?
Our ride heights are raised up a little, to 3 1/4" front and 3 1/2" rear (pretty close to the same forward rake as the last event, which was 3/16" and now we are 4/16"). We want the car a little lower, but that's as low as we can go in the rear with the new, stiffer springs, without losing too much preload. We may have to switch to a 7" spring in the rear to correct this. We jumped up and down on the frame of the car and rolled it a bunch before measuring, so they shouldn't change much. We will double check everything in the morning.
Oh yeah, BobnCincy - we took your suggestion and picked up the nylon tipped set screws. The provided ones had destroyed the threads on our sleeves, and it took us awhile to file them back smooth. That's why our collars were binding so badly.