As is well known, car manufacturers design turbocharged engines with low boost pressures in the range of 0.5–0.8 bar, aiming for low fuel consumption. However, during the tuning of the EA211 engine and with turbo pressure exceeding factory specifications, the stock valve springs are observed to be unable to close the valve properly during camshaft rotation. This results in misfires and a drop in power at high RP Ms. This retainer was designed and manufactured by RTMG Performance for the use of straight (not conical) springs, offering a linear spring rate in Newtons per millimeter (N/mm), and allowing for the installation of performance valve springs. Made from chromoly steel and heat-treated with stress-relief for maximum durability, these retainers are designed to work with OEM 5mm valve stems and factory-style valve keepers, while supporting inner diameters of 15.65 mm and outer diameters up to 24 mm. A complete kit with valve springs is also available for those seeking a full upgrade solution, under SKU 901-0941. Welcome to the next generation of EA211 engine performance upgrades. *You canot use it with original valve springs* Set including 16 retainers.