I'm going to assume you're trolling now. Seeing as how I can't recall any stock gm vehicle I've ever scanned that doesn't knock.
My 01 gtp made 205whp stock and knocked.
My 97 gtp ran 14.6 stock in the middle of summer and knocked.
My ls1 gto knocked with the factory tune.
The countless other l67/l32/l36/l26 cars that I've scanned/tuned all knocked while being bone stock.
Hell, my $60k ecoboost that I bought brand new, knocks some.
So, if any knock is not acceptable criteria, they did a piss poor job of enforcing it.