You're 15.5 years old man; do you really see the need for a pwo? Or know for what purpose you want a pwo? If you must take anything I recommend staying away from DMAA containing products and sway toward low dose if not non-stim performance products. At your age, I see little reason for needing to consume the caffiene equivilent of 2 1/2 red bulls. Not advocating red bull usage pre, just a comparision.
imo focus more on the training; perfecting motor patterns and correcting form before you stim yourself crazy while simaltaneously squatting with knees buckling all over the place.