PSI, the first racing-only valve spring manufacturer in the U.S., has continually grown to offer multiple series of springs to suit the racer and performance enthusiast alike. This spring is just one of PSIs 1500-series Max-Life offerings. It is built with all of the same attention to detail as the 1500-series springs are by using advanced heat-treating processes to strengthen the base material to increase fatigue life and offer better resistance to load loss, but with an additional proprietary multi-step enhancements to further the life of the spring. These processes target the endurance applications that these springs were built for like circle track and road racing. The ability to start and finish an event with the best spring possible to not only avoid breakage, but also avoid load loss, which compromises your engines performance is the mind-set behind this springs design.