it's state that Gouki holds back and only uses a small percent of his power when he's not shin. so the question is just how much percent of his overall power was he using in his fight against Ryu in SFA2. was it 5 % 10% or 15%?!? now for comparison for Gouki and Shin Gouki here are SFA3 Shin Bison, SF2 Bison and SF4 Bison precentage levels of pyscho power.
SFA3 Bison Pyscho power level 100%
SF2 Bison Pyscho power level 45%-55% ( max 60 %)
SF4 Bison Pyscho Power level 65%-75%