I had a GTS in last week that reads 95 no matter what we did with it,We even backed the CAS of as far as it would turn dropping power from 320rwhp to 246 ,Still 95 knock count,fuel is at 11.5-1 and 16psi with a HKS 2540 turbo.
We changed knock sensors, put a remote knock sensor on and it did not ping.so we upped the timing using the remote counter till it had a light ping and the PFC still read 95.
So this leaves me thinking dont ever trust the knock readout alone.