KP has done extensive testing with valves on the Kawasaki watercraft engine. We would say we are the leading experts on valves for these engines. OEM Valves are very high quality, and are recommended for both stock and racing application hands down. We HIGHLY recommend not using any aftermarket, stainless, or Titanium valves unless we offer them. Doing so will most likely result in either poor engine life or failure. Our racing valves are a premium Nickel Alloy exhaust valve for High RPM, Salt Resistance, and most of all Longevity. This is a BI-Metal valve with a super hard stem and tip to increase longevity. The Intake Valves have been completely redesigned to blow away OEM. They are actually Stainless Steel, have chrome stems for reduced guide wear (OEM is not a chrome stem), Hardened to prevent mushrooming, and more margin for strength. They also feature a bi-metal design so the stem will not rust from moisture. Leave it to KP to give you the Best Of The Best!