These springs are discontinued by Jim Wolf Technology. Please see the listing for the new JWT Beehive 370Z Springs here.
JWT Spring and Shim kit is for use with JWT race and street cams revving over 7000rpm.? Spring pressure measures 43lb on seat and 136lb at 12.5MM lift. The included shims replace the stock base shims to obtain the correct 36mm installed height.
For VQ37VHR C1 or C2 exhaust cams, includes 12 qty spring/shims