I am very stim tolerant and coming up on 6+ months of usage with no break. Norco, enhanced, alphamine, jack3d advanced and every other pwo i could think of stopped producing a mood lift/euphoria. My initial thoughts of this pwo at 2 scoops is that it is solid. I am about 30 minutes in and there is a good clean smooth energy. I will come back later and comment on the and endurance aspect during my workout.