Skunk2 is proud to introduce its Pro Series XP (Extra Pressure) Racing Valve Spring Kits for the Honda B16/ B17/ B18 and H22/ F20B VTEC engines. Each kit includes Skunk2’s high-quality race-proven dual valve springs that are the result of nearly two decades of racing and engine building experience.“XP” features a higher seat pressure for turbocharged and extreme high RPM motors. This spring has a seat pressure of 93lbs @ 1.320” while keeping the coil bind height for higher lift camshafts.Each Pro Series XP Racing Valve Spring is manufactured exclusively from super-clean, chrome-silicone wire milled in Japan. By using inner and outer springs mated together through a slight interference fit and with differing frequencies, Pro Series XP Racing Valve Springs are able to prevent valve float and maintain valvetrain stability at engine speeds in excess of 11,000 rpm. Wound by a premier North American winder, our Pro Series XP Racing Valve Springs retains its durability and strength that results in improvement to the extreme fatigue limit of the wire and enhanced resistance to load loss.Pro Series XP Racing Valve Springs are engineered to handle the demands of extreme-lift camshafts operating at prolonged, high-rpm use at championship-level racing. Skunk2’s Pro Series XP Racing Valve Spring’s for the Honda’s B-series VTEC engines are simply the best on the market. Pro Series XP Racing Valve Springs have been tested at speeds exceeding 11,000 rpm on our engine dyno, street, and the race track. Our superior, Japanese-milled, super-clean chrome silicone wire is 100-percent eddy-current inspected prior to coiling. Next, they are heat-treated, shot-peened, and chemically polished for strength and durability. A special nitriding process concludes Skunk2’s rigorous manufacturing process. The end result is a lightweight valve spring that safely accommodates high-lift camshafts and features superior resistance to load loss, even under extreme operating conditions.Skunk2 designs, develops, and tests its entire valvetrain lineup in-house to ensure superior quality and maximum performance gains. During development, each valvetrain component is tested both on the dyno and the road, including 11,000 rpm drag racing engines and 17,000 rpm superbikes. Manufactured from the best materials available, Skunk2 valvetrain components provide exceptional performance, reliability, and quality. These components remain standard-issue on each Skunk2 vehicle that we build and support.Seat Pressure: 93 lbs at 1.320”,Open Pressure: 238 lbs at 0.820”,Coil Bind: 0.718”,Must Use Skunk2 PN 312-05-0015 (Spring Bases) to Install These Pro XP Valve Springs in H22A/ F20B Engines