I got one in the shop right now with basically the same senario. It is an 05 with 3xxx miles that has a burned #3 and #6 piston. Come to find out the guy had a TST, EZ, AND a Crazy Larry program downloaded into the ECM. Before He brought it in for repair he took all of the power adders off and was in stock form. I had a hunch it was seriously overfuelled and that had been what had caused the problem but decided to have the engine go warranty anyway. I of course had to call STAR and they wanted to know if there were any signs of tampering, any codes, engine duty cycle, total run time,total idle time, total fuel used... . blah blah blah. After telling them what all of the readings that were saved in the ECM were, they deemed that the ECM programming had been tampered with. This was obvious to me and them because the total fuel used was 16 gallons and total run time was 3hrs. No way even close to being right. It was the downloader that made them void the engine warranty due to it altering the event data stored in the ECM. The guy at STAR said the use of boxes that do not alter the event data they are not really concerned about, like an EZ, TST, etc... But he did say if the customer paid to repair the truck using DC warranty approved parts and removed the programmer that the engine warranty would be reinstated. Go figure. This same thing also happened on a different guys truck that developed an injector problem. He was also using a Triple Dog downloader that altered the event data and DC said no when trying to order an injector under warranty. They also told him if he bought the injector out of his pocket and removed the programmer the warranty would be reinstated. I challenged this a couple months later when his truck devloped another injector problem (different cylinder) after the owner paid to replace the first injector out of his pocket. I called STAR and give them all of the specs and they sent an injector to me under warranty without any trouble. He had removed the programmer and they seen the specs agreed with the mileage since the last time it was in the shop. The warranty reinstatement thing really don't make sense to me but DC will do it if you get caught turning the fuel up and pay for the first offense out of you pocket and put the truck back stock or at least were they think it is stock. The bottom line is in my experince the downloaders are what made them cut the cord. FWIW, I am not one of those techs that go hunting for ways to get out of doing warranty work. Yeah the pay sucks, but if a guy has put some hop up stuff on his truck and if the parts he/she has added don't directly point to the problem I don't really cause a big fuss and go ahead and try to get it fixed for them. It kinda makes me look like a hipocrit when I blackout the entire parking lot with the old 12 valve when I'm leaving work. Oh well, on the other hand I was always taught "You play, You pay!" Live and learn.