Sports Contra Spring V.2 +1500rpm The current version of the counter pressure spring uses a modified alloy spring providing better resilience and above average strength. Replacing the spring is necessary when tuning engines, the idea is to prevent the initial response from the variator therefore increasing the engine speed, the the increase power with delayed engagement will increase the power at pull off. Markings on the spring help you identify the strength of the spring for example, a spring marked 1500 RPM will delay the reaction by 1500 RPM. The greater RPM spring will provide you with the greater power.