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 buildup for increased valve train life VALVE 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 steel SPRING 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 top SEATS & RETAINERS: • Made from 4041 steel (select applications use 707546 aluminum) • Designed to work with psychic stainless steel valves and springs