Skunk2 is proud to introduce its Pro Series XP (Extra Pressure) Racing Valve Spring Kits for the Honda K-series i-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 100lbs @ 1.600” 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.