A friend has an Evo 8 with a Snow meth kit. He was previously using the 375ml jet. He changed to the 625ml jet to see if there was any timing to be gained. Immediately after the change the a/f ratios displayed by his wideband under boost went from 11.0:1 to 12.5:1. I am thinking that it is not really running lean but that this has something to do with the Meth concentration getting very high and the fact that the stoichiometric ratio for Meth combustion is very different to Gasoline. Is this logical?

I want to check the lambda reading instead of a/f ratio, but haven't had a chance.