Originally Posted by Dragoneye
Not "will". "Can".
It's a very real chance, however rare, that you can
be denied warranty work.
Most people take that chance....I probably would, too.
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. That is just my 2 cents anyway!! Until someone gets hit