Like I say Lambda s fine and universal. However finding that number for many race fuels is not so easy. And the target number varies greatly from race fuel to race fuel. Just something to consider when someone says and average AFR is 10-1 it is fat, not knowing the scale being referenced it could be dangerously fat depending on the fuel used. He is not giving you a Lambda number, only an AFR which is likely based off of an inaccurate scale. Fat mixtures create alot of heat and can cause catastrophic damage. Much more so than being overly lean can and will. All Im saying. You are converting his number to Lambda not knowing what the idea lambda number is, and he is clearly not using lambda. I have not seen any reference to what fuel he is using so just speculating. I can tell you the fuel we use in the Vette if it sees anything close to what 10-1(.68 lambda) it will absolutely microweld rings and torch a piston, ask me how I know. FWIW this is with a fuel thats target is 13.31(.91ish). Tome its why scale and fuel used matter. Id be happy to se a lambda number but without knowing the fuel used it does not mean as much. Almost as little as a single O2 per bank on a maxx effort deal like this one.