GA T400 does hurt, but I'v efelt worse from GTP and QV prop. Definately got a huge baseball in my ass from Monday's shot. So yeah it does it hurt. It didn't seem to hurt as much the first day or so after, But yesterday and today it hurts more than it did prior. I've heard nothing but great things about this lab's products though, so I'm psyched to see the results. Their EQ 300 is painless. Their customer service is great and their TA time is outstanding.