Designed around high RPM engine durability and performance, BC valve springs are wound from only the highest grade, super clean, chrome silicone alloy and feature proprietary processing procedures for consistent pressures when your turbo is at full song. BC titanium retainers are CNC machined from 6AL4V round bar titanium to exacting tolerances. The titanium retainers will lighten your valve train significantly. We recommend upgrading valve springs and retainers when upgrading cams due to the more demanding conditions in the head.