Yes, I agree. When we tuned my S/C mustang did about 6 or 8 pulls tweaking at low rpms working towards wot. Then another 3 or 4 at wfo tweaking that. Almost 40 k on that setup. So unbelivably reliable, only 6 psi and as I recall kept the A/F just below 12:1. Traded extra power for reliability.

We are running NA engines at 13.3 -13.5 AFR at 6500-6800 RPM with about a 9.3 to 1 CR. We have never had any signs of detonation. Even at the 13.3-13.5 range the plugs are still mostly black. In my experience, a 12.5 to 12.8 AFR for a low compression NA marine engines is over safe and makes the transom black and wastes fuel.

Yea, probably agree with that. But my mustang is 10 to 1 and we can only get 91 octane up here. The only time I once in a while will get a little pinging is in 5th gear low rpm on the back side of the power curve and you get into it. Don't know about the canned tune that whipple does on the 500 efi kit but that's what I plan on running