Brian Crower BC0984 - Polaris Pro R (21-up) Stage 4 Full Drag Spec (pair)

Top tier spec for the all-out high performance, high rpm build. Requires BC spring/retainer kit. ECU and cylinder head work will enhance overall performance. Due to high lobe lift, it is mandatory that you change the valve guides and use BC valve seals. Failure to do so will result in retainer to guide contact causing damage to the head and/or cams. Must run with aftermarket pistons with proper valve reliefs built-in. Cannot be ran with stock/OE pistons due to possible piston to valve contact.