IIRC, VQ35DE rule of thumb is not to exceed 450 whp because the rods are fairly weak. Back then the safe tune was under 400 whp. The APS kit is sweet, though. It was my dream kit.
Also check to see if there's an intake plenum spacer installed like the one from MotorDyne. IIRC, the cylinders closest to the firewall usually end up running lean due to a "defect" in the design of the OEM metal intake plenum.
[EDIT] IMO... for 13.5k, you can use that money to fund turbocharging your 370Z.
__________________
|