The knock reading can be misleading as ive seen many cars with high readings with no det at all.One GTS read a count of 93 no matter what you did, we even backed the CAS off asd far as it could go and retarded timing with the PFC with no change,even changing the knock sensors did nothing.Use the reading as a guide only but its no where near perfect so us other means as a back up if your not sure.
A maximum power tune will give readings in the 50s also,this is why i like to use other tools for det detection on the dyno on hi powered cars.