KIT FEATURES: – ALL KITS SOLD WITH VALVE, SPRING, RETAINER, SEAT TO DO COMPLETE REPLACEMENT OF EITHER INTAKE OR EXHAUST SIDE – ALL COMPONENTS ARE MANUFACTURED UNDER ISO 9001 CERTIFIED FACTORIES – NITRIDE COATED COMPONENTS TO IMPROVE HEAT TRANSER & CARBON BUILD-UP FOR INCREASED VALVE TRAIN LIFEVALVE FEATURES: – FORGED ONE-PIECE CONSTRUCTION TO HELP WITH WEIGHT REDUCTION & IMPROVED FLOW – PERFORMANCE VALVES RECEIVE A SWIRL POLISH, SMOOTH STEM TREATMENT, AND ARE MADE OF 21-2N/SUH35HT STAINLESS STEELSPRING FEATURES: – SPRINGS ARE MADE OF SWOSC-V MATERIAL (OIL-TEMPERED STEEL WIRE) – SOME SPRINGS FEARTURE A PROGRESSIVE STYLE DESIGN WITH MORE COILS ON ONE END OF THE SPRING – PROGRESSIVE SPRINGS ARE HEAVIER ON ONE END AND SHOULD ALWAYS BE INSTALLED TOWARDS THE BOTTOM – NON-PROGRESSIVE SPRINGS ARE PAINT MARKED AND SHOULD BE INSTALLED TOWARDS THE TOPSEATS & RETAINERS: – MADE FROM 4041 STEEL (SELECT APPLICATIONS USE 7075-T6 ALUMINUM) – DESIGNED TO WORK WITH PSYCHIC STAINLESS STEEL VALVES AND SPRINGSExhaust Valve Kit Psychic MX includes 2 valves, 2 Springs, Retainers & Seats