Ive had my car tuned a few times,as mods were added.My car sometimes shows knock of 80 for a split second at high boost and RPM.
Taken the car back a few times to sort it out.But i was told all is normal.Could be a number of things in the engine bay making noise.
I never hear any pinging but i do get a read of 80 at high loads on occasion.
Tuner is very reputable.And works mostly on Nissans.