Originally Posted by steeleshark2
There have been many people denied because they kept a tune in the ecm. However, not ONE (at least posted somewhere) has ever been denied when they reverted back to stock. If it would be detectable, at least one instance would be posted somewhere and it would have spread like a wild fire. So, one can most likely imply that these tunes were undetecable by gm by going back to stock before warranty work.
"most likely", "imply"....there is still a risk, even if it's never happened.
They are not undetectable, and I wish I could find the thread that proves it...