[nlink720]

Correct Above: a stiffer rear spring rate is necessary to balance the car due to the different lever arms of the front and rear suspensions. The fronts spring perches are farther out than the rears, so for a given spring rate the front is more effective. I heard somewhere that the front is about 0.95 while the rear is like 0.75. That's why the rear springs must be stiffer to maintain a neutral balance. 500 on all corners will understeer unless you are running a very stiff rear bar and relatively soft front.

I have my bars equal, and 550F and 700R is neutral to very slightly understeer at the limit. 550F/650R was great all around until the limit, when it understeered annoyingly enough that I went up 50lbs, and it was resolved nicely. I use my car primarily for autocross, so a more neutral car may be desired for my uses more so than for a primarily tracked car. But, none of this is important until the limit -- there is no way to differentiate other than ride firmness -- the difference between a square spring setup and a softer front-stiffer rear setup in a street-only environment.

I've been through 440/550, 500/650, 550/650, and 550/700.