I believe i picked up almost 12 hp from stock. It was a pretty good gain. But I aslo added the YEC kit harness an ecu at the same time. So I am not sure of how much the YEC contributed to the power. I have not heard the Yosh system so don't know the comparison.Was there a noticeable power increase with the Graves Full System??? How did you like the sound was it a deeper tone than what you would get with a Yosh system?