Nobody has ever "proved" stealth tunes are untraceable. You can claim it all you want, but I challenge anyone to send their stealth tuned info to GM and dare them to check it.
If you prove you tuned it, and GM verifies it's still "stock", then let the evidence speak for itself. If they don't look for it, then maybe. But if you dare them to look for it, I'd be interested in the outcome.
Until then, I don't care what ANYONE says that they can't detect an aftermarket tune. It's pure BS.
Unless, of course, the Diablo doesn't actually tune the car...