Nailing my double Gs on my teacher's Olds Special. Then I greased a double C.
The embouchure reset I figured out has made all the difference. I have also been pleased with my ability to get an increased amount of air through the horn as a matter of instinct. I used to crunch up and contort half my body to squeak around in the high register with minimal air, maximum stress, and nominal sound...not anymore. I am able to generate the airflow and massage it into just the notes I want, mostly ;)