its ok for it to not be connected because you could over boost. The plug your showing connects to this by the turbo which should be about dead center down the side of the motor.
I cant really find you a pic of where the above is located to make it easier for you but as I said just look down the center and side of the motor they are on both sides but again if you have a boost controller they are not needed and should remained unplugged do to over boosting.