This is a full set of 24 titanium retainers and 82# valve springs for your LF3 or LF4 that comes in the 3.6 twin turbo which is in the ATS-V, CTS/XTS V-Sport. The factory valve springs float at around 6000rpm when you turn the boost up in those engines. These valve springs will add roughly 1000 more RPMs to your powerband. It is hard on valve springs when they float (they can break and drop a valve into the cylinder), so these valve springs will not only improve performance, but also the reliability of your car.