PROX Valve and Spring Kit 28.SIS3405-2

If you're pushing your engine to high RPM territory, factory valve and spring assemblies become your limiting factor. The PROX 28.SIS3405-2 replaces weak OEM components with nitrided steel valves and premium chrome vanadium springs engineered to handle extreme conditions without degradation. This is a straightforward bolt-on upgrade that uses your existing retainers, bases, and seals—no machine work required.

Steel valves deliver superior durability and wear resistance compared to their softer OEM counterparts, especially critical in forced induction or high-boost applications. The matched spring set is purpose-built to manage the additional mass of the steel valves while maintaining precise valve timing across your entire RPM band. You get the reliability of a complete valve train upgrade without replacing your entire cylinder head assembly.

• Nitrided steel valves
• Reduced valve wear
• Chrome vanadium springs
• High-RPM rated
• Extreme condition durability
• OEM-compatible installation
• Bolt-on design
• Intake or exhaust option
• Uses existing retainers
• Uses existing bases
• Uses existing seals
• MPN: 28.SIS3405-2