i ended up taking the amped by met-rx. the sample pack says to take 2 servings (full pack) but i took half to test (1 serving) felt like it worked pretty well...felt fairly strong thru the whole workout...which is all good, i got a lot of those packs and if each one is 2 servings, i'm good for a couple of months
i've heard good things about the superpump 250 but since the met-rx product was completely new to me, i wanted to try that first
the iss product doesnt seem to have anyone talking about it but its free so we'll give that a shot also