Are you still making full boost? Any whistling, whooshing, or howling sounds when more than 50% throttle? If so, you blew an intercooler connection off and just need to reset it.
I just went stage two and I've had two occasions so far where I've heard a loud pop at full throttle and then full power died off. Afterwards, I couldn't make full boost anymore and I could hear the whoosh coming out of the engine bay. The first time I blew the connection off at the intercooler. The second time I blew it off at the throttle body. Good luck.