When I took Tren, that shit there burned every time I pinned, I expected it though. Got very powerful strength and no back pumps, though I did get insomnia and at times anxiety peronally. Whatever the case is here, I like how CK and you both are finding the culprit. MAybe the Taurine powder will help. One thing on Tren, it was sore for 3-4 days and I was using TREN Enanthate, not Ace. So, both esthers hurt. Your pics look solid, good looking gains and lean mass.