Time to upgrade the suspension ...

cv129

I think under steer with our car is with the OEM alignment. Track guys advise to use stiffest front bar on this car, which effectively raise spring rates anyway. Some even disconnect rear bar all together. And some extreme examples, check out (link below) what kind of front to rear rate split the really serious guys run. Within the thread, member Jhro and GSS have no afternarket aero so I think their setups relate to you the most. Also note rear spring location (true type or OEM, can't compare the two rates directly).

Dedicated AutoX/Track Spring Rates

As for the Zeal 12k or 10k....I hesitate offering a blanket opinion. If you ever lower it, or decide to have race wheels and tires in smaller diameter (lower height), or have big wide sticky front tires (bigger braking power), or you become Lewis Hamilton, I think you will overwhelm 10k fronts. But if you are sure you will stick to stock height, tracking just for fun and not for chasing lap times, and you want maximize comfort for your lady friend/wife, then maybe 10k is fine. Below is a link to various spring rates for reference if you don't already know.

Spring Rates

My guess is, for Zeal, 12k should still yield fine ride quality. My fronts are approx 11.6kg/mm (OEM Nismo 8.6kg/mm). At full stiff (JRZ RS1), my butt feel is the dampers still take high speed compression better, and have better control on rebounds.

Edit: Echo on Ape's response, I find it kinda weird on Zeal's spring rate decision...I assume the rears are OEM spring location. It would be really really weird if the rear rates are for true type.

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