Save the Manuels
The tuners do code out the CEL. The issue is when you get plugged into the machine for the inspection and your OBD readiness is not set. It's an automatic fail.That is absurd. A tuner needs to offer a tune to tweak the values so the CEL doesnt pop up. My buddy has a BMW and those tuners do it and dont even care. Not sure why mustang tuners are so scared to do it.