Supertech Black Nitrated Intake Valve +1mm Size Set of 8. Note: Must use single groove keeper part# KPR 6S 7 (two per valve) We apply more than 30 years of experience in the development of each and every Supertech racing valve we sell. Combine this experience with state of the art equipment such as ultrasonic tests, x rays, laser measurement equipment, and applications like computerized Finite Element Analysis (FEA) and it is no wonder why supertech has some of the best performance products on the market. While this is more than most manufacturers we dont stop there. We also do extensive testing working very closely with many of today's top engine builders in order to continuously improve our products. All of this is meant to insure Supertech's industry leading reputation for high flow rates, durability and uncompromising quality. Engine Valve Manufacturing Production of our racing valves begins with a one piece forging, where the head of the valve is forged under a slow two step process to keep a good material grain flow. The forging is then CNC machined in several steps to ensure the precision of the final dimensions. We then do another heat treatment for stress relieving followed by a nitride hardening treatment (or coating process depending on the application). Lastly, we do one more grinding, followed by our patented Superfinishing of the surface to ensure that each valve is free of any imperfections and the dimensions are precise. One Piece Valve Our valves are not finished from generic blanks rather they are specifically designed for each and every application. We work relentlessly, testing and researching every aspect trying to improve the air flow of our designs. Durability With every valve design we strive to maximize durability through higher fatigue resistance and tensile strength. Each valve tip is hardened beyond 52HRc. Strict Tolerances Its unlikely you will find any of our competitors valves with stricter dimensional tolerances than our Supertech valves. Combine that with finished seats with equally strict run out tolerances and you wont find a better sealing, better performing and easier to install solution anywhere! Superfinish In 2006 we introduced our stem Superfinishing as a standard addition to all of our valves and provided it at no additional cost. When our Superfinish is combined with our Black Nitrided valve it reduces the surface roughness to 1 3 of our chrome coated valve. The end result unsurpassed performance and durability. Higher Flow Rates Optimum high flow rates are achieved by ensuring that our valves are manufactured with the best angles for each application. We consider back cut, under cut and valve head angles for each application to produce the optimum high flow rates for each application. STAINLESS STEEL VALVES: Our intake valves are made exclusively from an enhanced versions of EV8 (21 4N) steel. This is the highest grade of steel available and provides the strength to withstand just about any application. Our exhaust valves are made from EV16 (21 8N) or EV8 Nb w for greater strength at higher temperatures. Some applications call for us to harden certain areas such as the tips and or the seats. For these applications we will often times weld other hard metal alloys to the valve for increased durability. Black Nitride Coating This is a hardening treatment that has been steadily growing in popularity over the last several years. These black Nitride coated valves feature harder surfaces and smoother finishes, providing less friction and subsequently longer life. Please see below for more benefits of our Black Nitride valves. Vehicle Fitment: Audi A3 8P (2. 0 TFSI EA113 EA888) Audi A3 8V (2. 0 TFSI EA888) Audi S3 8P (2. 0 TFSI EA113 EA888) Audi S3 8V (2. 0 TFSI EA888) Audi TT TTS 8J (2. 0 TFSI EA113 EA888) Audi TT TTS 8S (2. 0 TFSI EA888) Volkswagen Golf GTI Mk5 (EA113) Volkswagen Golf GTI Mk6 (EA113 EA888) Volkswagen Golf GTI Mk7 7. 5 (EA888) Volkswagen Golf R Mk6 (EA113) Volkswagen Golf R Mk7 7. 5 (EA888)