As you well know it's a combination of other things as well such as sway bars, rake, ride height, tires, etc, etc...
Currently I'm running the trophy sway bar upfront and the Zinardi bar in the rear. Have CT front camber bushings installed as well and set at 2.5 negative in front and 2.25 the rear. Tires are wearing even and tire temps are right at 200 across the board. Ride height is set higher than most to clear the 275x35x18 and 315x30x18's I'm running. 5-1/4". Right now my rake is at 1/4 inch, which I'm about to lower to 1/8" on Billy's continuing advise. Also running NT-01's.
I have tried the 457/457 they came with. Front end was too weak, I was killing my front fenders and I hate oversteer
.Tried 557/457, front end was still too weak for my liking. Changed to 657/457. This balanced the car out very well. I moved up to 857/457 and the front end felt numb and started to push too much. Went through a series of Sway Bar adjustments, Compression and Rebound adjustments but still didn't like the way it felt. I dropped back down to 657/457 for the time being and it became neutral again and very well balanced. I may try 757/457 here soon. Have the 757's sitting here, just haven't put them on yet.
I running 2 clicks from full stiff on the front and 4 on the rear for compression and Rebound is set at 3 front and 5 rear at this point.
As Billy has explained to me.
More rebound = less roll, quicker response, but less grip.
More compression = better response, bumpier.
So at this point I'm just concentrating on Compression, Rebound, Rake and Tire Pressures getting them to all work together.
Have the last NASA-AZ event of the season coming up and I'm leading the UMS TA unlimited class by 35 points with the last event being a double points event so now is not the time to experiment again or try and fix something thats working.
Best lap times so far for me have been the 657/457 combination by over 2 seconds over anything else I've tried so far on the 6 tracks I've been on with the KW's this year.
We all feel something different with our individual style of driving, so what works for me may not work for someone else, as you also know
...........so far what spring rates have yielded your best lap times?