it runs 14.1 at WOT? I doubt that. Coming from tuning my mazdaspeed6 that thing ran 9.5-10.0 at WOT, but we would lean them out to 11.6-12 which was still safe, I know different cars, but I don't think any car runs that lean at WOT. That is more like cruising AFRs.
By leaning out you improve the combustion efficiency, by getting a more efficient burn, but you run the risk of running hotter. Adding power isn't just tweaking timing, there is more to it with fueling and other things.