I apologize ahead of time is someone has already talked about this but I have done a few modifications to my Duramax in the last few weeks. I cut the muffler out and installed the straight pipe conversion. I love it, it roars when you get your foot into it. I also added the K+N FIPK Generation II kit to it which really enhances the sound of the turbo and has much better throttle response. Unfortunately I couldn't wait till my extended warranty ran out. I bought the truck with 37,000 miles on it and decided to buy a GM backed five year or 75,000 mile warranty. I have 51,000 miles on it and obviously I will reach the mileage well before reaching the years on the warranty. I read a lot of topics from this forum and I often wonder if I should have waited to put these mods until my warranty was expired, but like most coundn't wait for the roar and power. Maybe I will get lucky and not have too many problems. None to date so far. I am very good about servicing the truck and changing the fuel filters four times a year. Lets hope for the best. I fear the worst, because I know the dealer will void my warranty. GM is the worst dealers of voiding warranties due to customer modifications. For all those who have installed modifications on your trucks I wish you the best also. Nothing like having serious power and attitude to brighten up your day.