I have datalogged my car enough to know that I don't have detonation. The top end timing doesn't induce any detonation. In researching this, I came across
this video by Hastings in piston ring failure.
https://youtu.be/3GbXxf435N4
One of the causes listed is "lugging" the motor. During some datalogging sessions, I have "lugged" the motor intentionally. Sometimes 6th gear at 900rpm
as a way of gathering readings on VE cells not typically used in normal driving.
So I'll be avoiding that in the future. Why just #7?