4PISTON Oil Pump. The stock K20 oil pump is a great piece for up to 9,000 rpm bursts. Beyond 9,000 the stock oil pump starts to cavitate. Continuous duty at high rpm and in endurance racing with very high oil temperature, this cavitation can be catastrophic. Our ported pump will allow continuous use above 9,000 rpm, and we have run the pump beyond 11,000 rpm with great success. We start with a brand new OEM oil pump from Honda, disassemble and port and notch for fitment on both K20 and K24 engines. The pump is then cleaned, oiled, and reassembled. This critical part is cheap insurance for your multi-thousand dollar investment. In a straight back to back comparison, this pump will make 3-4hp more than a modified S2000 pump.