In 2007, technically the 2007.5 model year, Dodge introduced the 6.7 Cummins for the Ram pickup truck. Due to EPA federal mandates and stricter emission regulations, various components were added to the 6.7 Cummins. These parts include: Exhaust gas recirculation (EGR), Diesel particulate filter (DPF) & Catalytic converter (CAT). When your diesel pickup is relatively new with low mileage these systems function fine. Unfortunately overtime, fuel mileage starts to get worse, DPF regen no longer works like it use to and general drivability is poor. Depending on how plugged your CAT / DPF is, your fuel mileage could be around 12-13mpg. Often times worse. To top it off; turbo failure is rather common because of the EGR system. Dealers will recommend cleaning out the DPF, this quite honestly is just a band aid fix. In a few thousand miles you will have the same issues. However, this still doesn't address the EGR system. Often times cleaning the DPF isn't an option and replacing the DPF is sometimes required. This can cost thousands of dollars. If your covered under warranty great, but what happens when your out of warranty? Hands down, the best upgrade you can do for your 2007-2009 6.7 Cummins is a DPF & EGR delete.