There have been many many stock low mile cars who have detonated themselves in the C6 Z06 world. In the Vette is is so bad that many have taken cars back to the dealer to have guides checked.
Many low mile cars have valve guide issues, whether they are stock or not. Modified does accelerate the already present issue as the guide is not concentric with the seat. There have been class action lawsuits over this issue.
When a C6 Z06 goes up for sale the very first question asked is "have the heads been fixed, how long ago was it and who did the work?"
21,000 miles
GM TSB addressing the issue
https://static.nhtsa.gov/odi/tsbs/20...13675-9999.pdf
There was also a "wiggle test" developed for these engines, you can Google it.
When you get enough valve guide wear the valve cocks over and the rocker will unkey the valve, then $$$$
https://www.corvetteforum.com/forums...ure-stock.html
https://www.corvetteforum.com/forums...lve-issue.html
Imagine how many had no idea Corvette Forum or that thread existed? I wonder what the multiplier is? The LS7 is the exact reason I bought a C5 Z06 for a track car instead of a C6 Z06. Blow up a LS6, 7K. Blow up an LS7, 15K.
There are multiple threads on this issue on Corvette Forum.
The coating also fails on the rods causing big $