A bonnet assembly for assisting to move a valve stem to a retracted position includes a bonnet body. The bonnet body has a bonnet valve end selectively connected to a valve, a bonnet actuator end opposite the bonnet valve end selectively connected to a valve actuator. A valve stem extends through the central bore of the bonnet body. A booster piston seal circumscribes the valve stem and engages an inner diameter of the central bore. The booster piston seal selectively defines an extent of a pressure cavity containing pressure media. An effective stem pressure surface faces in a direction towards the valve and is in fluid communication with the valve when the bonnet body is connected to the valve. A booster pressure surface faces in a direction towards the valve when the bonnet body is connected to the valve and is selectively acted on by the pressure media.