Quote Originally Posted by MassiEk4 View Post
Also true.
But I think it would be foolish not to upgrade springs and retainers or even valves when upgrading to after market cams; you would want to be able to rev higher than oem red line to make good hourse power, especialy if you are going all motor.
They're not necessary. The new camshaft might not need to rev out to 9,000 to make some kind of power, and even the OEM gear can take a little extra punishment.

Keep your valves OEM.