If you want to hear the turbos on your Raptor Ecoboost or F150 Ecoboost then you want a Turbosmart BOV. When your foot backs out and the throttle closes that excess boost is usually recirculated back into the intake, but with the turbosmart BOV that boost is vented to atmosphere causing the wonderful SPPPPPSSSHHHH turbo noise bringing a smile to your face and turning heads all around you.