I'd certainly feel more comfortable if your AF's were closer to 12 at WOT in those RPM ranges. See that dotted line? You want to be below that. I'd richen it up a bit via the tuner and see where that takes you. I know you don't want to pay more for gas, but you REALLY don't want to be paying more for an engine.

My stock Saleen tune was at 13 a/f and that was categorized as being "aggressive". They changed the tune and injectors in 2007 for a reason. 05/06 ran too lean to be safe. You're at 14 or above during your WOT pulls which, IMO, is toooooo high to be considered safe and reliable.