knock meter on power fc

[NIS.26L]

I have a apexi power fc for my r33 gtr and i was concerned about the knock meter getting up to 68 three times last week the car is making 254 klw at all 4 wheels at 18 psi with stock turbos, blitz air filters, and bigger air flo meters,3inch exhast.

when i drive it at 16 psi it only rarely go's up to 20 on the knock meter.