not possibly... it does... youre altering, or basically deleting your factory calibrations from GM, and uploading a completely new one that takes out Torque Management, alters your fuel/spark ratio's, etc... so yea, warranty goes bye bye.. UNLESS... whatever happens to the truck, if the dealer can prove the tune didnt do it, then youre ok, like say your wheel bearing goes bad... well the tune didnt do that, so its covered under warranty... but for me, i spun a bearing in my SS and i was tuned... end of story there lol... there are ways around this... but while its the best mod for the bang for your buck aspect... it also can hurt you.. just a risk you gotta weight your options on...