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Blower Cam Shootout--HorsepowerStock H.O. vs XE258HR vs XE274HRObviously even positive displacement superchargers like aggressive (but not too aggressive) cam timing. The XE258HR increased power from 438 hp at 6000 rpm to 456 hp at 5700 rpm. The difference in the peak power rpm was valve float. It is likely that the peak power might have exceeded 460 hp with the XE258HR cam had the stock hydraulic roller lifters not given up early. Adding new lifters allowed the XE274HR cam to rev freely to 6000 rpm (but not beyond). The supercharged motor pumped out 485 hp at 6000 rpm with the XE274HR cam. The boost pressure dropped from 8.5 psi with the stock cam to 7.5 psi with either of the two Comp Cams. Oddly enough, there was no drop in boost pressure between the two Comp Cams.