Originally Posted by trackdood
spring rates on the KW for IS250/350 should be around 8 and 6. remember KW always has softer springs but valving is super stiff. so dont judge them by the spring rates unless you are racing the car at a RACE event otherwise the rates are fine. WILL NOT work on a IS-F
Thanks trackdood.. and he's info is very correct... since I had them on my S13 as well...