I just stopped using NO Shotgun last week, and have noticed an extreme lack of energy during weight lifting this week. I also have been getting headahces during my workouts. I am guessing this is from not taking the NO Shotgun pre-workout. If this is the reason, that is some powerful stuff. I have taken other NO supplements (SuperPump, NO Explode) and did not expierence this dramatic change. I have kept my calorie and protien intake the same. Has anyone else experienced this or could it be something else?