I just bought a 04 duramax with 68k miles. I understand that the duramax has a warranty for 5yrs or 100k. My truck has 4" bully dog stainless exhaust, a bully dog programer, and a AFE Stage 2 air box. I know if I bring it to the chevy dealership I need to return the computer to stock first, but do I need to put the original air box back in? Someone told me that if you put K&N filter in it would void the warranty because the K&N filter oil can screw up one of the sensors. Does anyone know the answer to this?? Thanks Andy