It's my understanding that a dealer may not be able to tell, but if the ECM is requested by GM and sent to GM, then the engineers there can tell. I believe that occurs sometimes during powertrain warranty claims. There has been discussion of this within a number of other threads, though I couldn't tell you which ones. I have also heard that the TCM does have a flash counter, so those with the automatic should consider this. My feeling is if you are very concerned about warranty, then don't tune. If you are not, then tune away; but don't think you'll get it by GM should there be a future powertrain claim. If you break the rules then live with the consequences...
OP - sorry for contributing to the thread jack...
