what AFRs are u running now on 15psi??
if it is running richer than what it was before, that would explain why you're down on power 'cos the leaner u run the engine, the more power u can make but at the expense of reliability.
Also, as sydneykid would say, it's not about the peak hp, it's about the power under the curve (average power).
all in all, it's a good effort dude, happy driving.