Originally Posted by jimmyjet
From whatever you were saying, I gather you experienced "valve float".
God did not intend XF's to be wound beyond 6,000 R's.
Assuming he has an SRT6, there is no valve float to worry about at that RPM; the C32 AMG (same exact engine) revs to 6,200 RPM stock with no problems. My rev limiter is actually set at 6,400 RPM with no issues. The Germans have a skewed perception of god, hence WWII.