I personally wouldn't want to run 12.5 AF on my car.I watch a few good tunners dial blower cars in and they all seem to go around 11.5.
I was told the dynojet uses 2800lbs for load,that would mean that our 3600+ cars under load,off the dyno may actually get a bit leaner.
With the tunning we have done so far with the 03's,they do seem to like to be a bit richer.
Example.I changed AF on my 03 from 11.1 to 11.6 without picking up any power.Even if i got better dyno numbers running AF @ 12.5,I feel safer with low 11 AF numbers.
JMHO...