I have an '05 GMC with a Duramax. I put a programmer in it and that worked out okay. Then I put a 4" exhaust on it. Then came the problems. I couldn't drive the truck for more than 30 minutes without a trouble code popping up. After doing some research, I found out that the new Duramax, the LLY, has some features that the LB7 doesn't have. The main one being that the turbo has a variable output that, along with the EGR system, requires a reading of the exhausts back pressure to work properly. Back pressure is what I'm trying to get rid of. Does anyone have a solution for this problem? Maybe a way to trick the sensor into thinking there is back pressure?