The 2000 SS with the LS1 has 2 belts. The AC is driven separately from the rest of the stuff so removing the belt and AC drag(I know it has a lock up clutch but there is still parasitic drag) has to free up at least 1-2 hp.

AC was not available on any solid lifter chevy's back in the day. AC was not available on 67-72 Z28's or 396/375 hp cars or 427 COPO cars.