It think it might be, which might be the real reason why michael.gonzalez's motor let go. They said the boost cut threshold wasn't there and it lifted the head, but it could be cylinder pressure/detonation from running leaner.
Reason I'm not believing the boost threshold story is in the E85 tests, you can see the power dying off:
Scaling makes it look worse than it really is, but I don't think that wastegate is open. If the boost pressure was lifting the head, then the E85 tune would definitely lift the head.