i am not sure how many hp you would pick up but if you arent using it, bypass it and take it off, along with the other smog stuff and save some weight.
mine is bypassed with a short belt, and though we did several different dyno sessions that day, even before and after the bypassing of the smog pump, i couldnt tell you what i picked up because we also changed the crank pulley to a small ass coke can size race pulley and a different alt. pulley and I picked up 16 to the rear wheels. from the pulleys and smaller belt.