I just ended a month run of this combo and absolutely loved it! I eased up at first on leg training day as though are the days I am most likely to get light headed during heavy squats. However, even on the most intense days, stacking the two together worked really well for me. I never once felt jittery or lightheaded and my stomach was not upset at all from either. There was just enough drive there to let you know it was working and to keep you going, but not so much that it overwhelms you. The flavors of both were equally great and combined together well. Honestly my only critique of this combo is that they come in containers that have different serving sizes lol. Really great products iForce and highly, highly recommended!!!