best AFR for Power??

Thanks for posting that chart. It's an important reminder that AFR's don't necessarily mean anything without knowing what fuel the engine is running. If one person says their car runs it's best mph at 12.0, without knowing the fuel type, what does that tell you? Even 10% EtOH makes a difference.
Yep, for our lovely CA gas I had to change the AFR gauge reference from 14.7 to 14.1.