I hear ya on the lower back pumps with higher carbs though. I'm at 400g per day on carbs right now at end of week 5 Test/Tren/EQ and lower back pumps have been so bad at times it's nearly ran me out of the gym....especially on squat and back days. I started mega dosing the hell out of Taurine and it has helped reduce them, but they are still there, just where they are at least manageable now