PCE Aluminum Roller Rockers are extruded from 6061 T6 Aluminum. The larger needle bearing fulcrum can withstand valve spring loads up to 600lbs, while the extruded body has a tensile strength over 60,000 PSI. Ideally suited for use with Solid / Mechanical flat tappet and Hydraulic Roller Cams. They feature very precise valve operation, horse power increase of 10-15, increases valve train life dramatically, acceleration is more responsive, oil temp will run approximately 5-10 degrees cooler NOTE: Rockers are designed to eliminate need for guide plate. Perfect for mild street application where guide plates are not desired.