Yes it is Art. No cure was used to create a "pho ring". It just had a Santa Maria rub.
Even though the PTG was out of control for most of the cook it was really bellowing smoke
And the meat was foiled at 120F IT so that ring was created during the first few hours.
That case fan I added changed the airflow of the cooker. Going to have to add a switch for it and only use the case fan during high temp grilling when the extra air will be helpful and keep the PID cool