Okay, I just got my first duramax. I recently had an old 6.5, loved the truck so I decided to stick with chevy. I have a 2003. I'm trying to learn about some limitations and first upgrades I should do. So far I have replaced the exhaust with 4" mbrp from the downpipe back, and just recently installed an Edge Evolution CTS tuner. I've heard you should get the heads studded and a couple other must get upgrades. I'm in the military so I don't have a whole lot of money but I want to get some ideas to save up for. Thanks in advance!