In 2010 the EPA released stricter emission standards for manufactures to follow. For the 10-12 6.7 Cummins updated emission components have been installed. These trucks are equipped with: Exhaust gas recirculation (EGR), Diesel particulate filter (DPF) & Catalytic converter/s (CAT). When your truck is relatively new with low mileage these systems function as intended,. Unfortunately with increased mileage fuel economy starts to get worse, DPF regen no longer works like it use to and your faced with poor drivability. As your DPF & CAT get plugged with soot your fuel mileage is also reduced. In addition to poor fuel economy, turbo failure is rather common because of the EGR system. In an attempt to remedy this dealers will recommend cleaning out the DPF, this quite honestly is just a band aid fix. In a few thousand miles you will be right back where you started with poor fuel mileage and a turbocharger waiting to fail. The best thing you can do for your 2010-2012 6.7 Cummins is a DPF & EGR delete.