This was for my 06 350 DRW. So far so good. I did noticed better mpg while on the highway. The lie-o-meter did not show it but the fuel remaining in the tank did. I took a trip up to Virgina, 6 hours round trip, and when I got back I still had just little over a 1/4 of a tank. When I did the same trip, pulling the same load, with the 4:30s I would have been on empty. It was expensive to do. $1800. But over the life of the truck, and diesel prices, Im sure it will pay for itself. 90% of my driving is on the highway. Next is the rest of the mods. Tuner,exhaust,gauges and intake. They have been ordered just waiting for them to come in.