Street guys need not apply.
If you're a serious racer, you'd better be sure you're using strong valve spring retainers, such as these COMP Cams titanium retainers. They're stronger and lighter than steel, which means that you'll gain speed and power. They use COMP Cams' Super Lock technology and are designed for 10 degree valve stem locks. These retainers work best with COMP Cams' valve locks and optional lash caps, and you can be sure that they won't split at high rpm, tearing up your engine.
Valve Spring Retainers, Titanium, 10 Degree, 1.550 in. Outside Diameter, .710 in. Inside Diameter, Set of 16