Locks you say make no difference ??? I disagree totally. 7 degree locks on Steath heads are the cheap stamped steel rounded corner valve locks. If you stay with 7 degree retainers, buy 7 degree (machined) sharp corner locks so they fit deeper in the valve lock groove of the stem. Using stamped steel rounded corner locks bur the valve groove by riding up on the upper outside of the valve groove area. Which means it's trying to pull the valve stem through the valve locks. When you start putting more aggressive cam profiles against the standard Steath components changes must be made with springs, locks, and depending on application, retainers. The heads are fine the way they come for stock application cams, but why would you buy an aluminum performance head for stock cam application ?? So again components must be changed (Springs) to match the cam your using and it would be a good idea to change locks also. Check the spring rate of the springs on the steath heads against what the XE274 calls for.

logan426