with the timing mod, gas is good, so no worried there.
as far as the knock goes, there's rod knock which is realy no bueno...then theres "knock" which people use to explain ping/detonation. as you said, knock typically won't go away with engine rpm/temp....just gets worse with speed. and detonation at low load is pretty hard to do as well...so kind of at an impass.
why not ask the guys at the dealer to have a listen? my 6 was always loud, and when swapping the top end components it just got louder. my miata has a ticking sound until it warms up, then goes away.