I have been studying replacing my injectors on an '03 Duaramax. I would like to understand what and why the injectors go bad in these. So far I have read that dirty fuel, no lift pump, water, etc are the issues. Also, I have read that the HP fuel lines corrode and are a culprit. I would like to know if anyone has any further explanation, so when I replace the injectors, if there is any other precautions that can be taken I can do it. Right now, I am planning on replacing the injectors, probably the cups and the HP lines in the heads, as I only want to do it once for longevity. I also am considering adding a lift pump and a FASS 1 micron filtration system (as I have read that the Bosch Injection system was designed for this rather than a 4 micron as GM has installed). Any advice or explanation would be appreciated.