What is the optimum Air Fuel Ratio at WOT?

[BrutalMetal]

I'm getting ready to do a few dyno pulls at my friends shop and wondered what readings you guys like to see? I want it as lean as allowed without doing harm, I have a normally aspirated 99 SVT Cobra with the U7146 Tuner, Thanks CJ

[sohfast94]

12.9~

[BrutalMetal]

Thank you Brain that's the range I was thinking, so 11.0 is too rich? One more question, what is the most aggressive spark advance I should be seeing at WOT through the powerband? Presently when I datalog my Predator I'm at 20 degrees, I've heard up to 26 is OK? Am I correct or is that too aggressive? Thanks!