Enhance Mitsubishi 4G63’s performance with Supertech’s high-performance valve spring kits, the preferred choice of the world's best engine builders. Crafted from premium Superclean Chrome Silicon Vanadium Steel alloy, our valve springs kits deliver exceptional durability and performance at high RPMs. Each spring is computer-designed to maintain optimal wire stress levels and controlled harmonics, ensuring superior stability and longevity in extreme conditions. Paired with our high-quality, CNC-machined Titanium alloy retainers, Supertech valve springs provide your racing engine with a significant competitive edge in both performance and durability.