Minimum Rear Grip?

Funny, in my main Yokomo Driftmaster, I have it set up for the pretty much as much traction as I can get in the rear. And for precision driving and speed that is definitely a great set-up.
But now that I am trying tune my CS Cyclone for a Counter Steer style, I am trying everything I can to reduce rear grip. Looking at my two cars, the rear suspension set-ups are complete opposites. It's pretty interesting when I think about it...

My latest change has been to put even a stiffer rear spring. Now I have a Yokomo Ti -Hard in the rear and the Soft in the front.