The boost controller, and the boost solenoid are only controlling how long the solenoid is open as it pulses. It's effectively pulse width modulating for air. This is why you set it by duty cycle, not by PSI. Everyone's settings will be different based on their setup. In this case Elliott maxed out his system, because the duty cycle was set to 100%, meaning it wasn't pulsing, it was just straight up open, which means there was no more air pressure to allow through.