I 100% agree with that. Plug reading is as much an art as it is a science. We can’t see into the chamber. What we can “see” in the chamber is just a very tiny window of the chamber, local to the plug. What happens further away from the plug may not (probably is not) the same as what happens near the plug.
Sooooo...you may not be able to get the “perfect” plug or the “perfect” a/r ratio on the meter (is there ever a “perfect” in any of this?????) so MPH is the best way to settle on WOT jetting. Even when looking at cruise and idle, the plug may not look “perfect” but it has to idle and cruise clean and not stumble or choke you out with fumes.
I haven’t had a chance to go strip with this guy yet. I’ll get a better handle on WOT when I do. Certainly that will be by MPH. And then I’ll let the plug say what it says and take pictures so the owner will know what to look at.