I've had 2 6.7's. First one was an 07, the first 3 months I had that thing it was in the dealers shop more than in mine, for emission related issues. After the 4th time being told it would need a new exhaust system and turbo, but only doing a reprogam to fix it for 3-4 days, I ordered up an H&S XRT and turbo back exhaust. The best I could get out of that empty was 13mpg, towing my 32' haulmark with 6 sleds it was about 7-8mpg. After doing the delete's/exhaust/programmer I jumped up to about 15 empty and 9-10 pulling. As time went on (did the delete's at 10k) the thing kept getting better mileage and once it hit about 40k I was up to 21-22 empty consistently and 12-13 towing which I was happy with. And the power.... sweet!!
Then, at 107k miles I decided I would try a new one and picked up an '11. Brought it home and immediately deleted and tuned it exactly the same as the other one. Mileage prior to delete's was again around 13 empty but after deleted I only gained 2 mpg at best, it has been getting better since it hit 30-35k miles and now with about 45k I'm getting around 18 empty. I'm hoping for 12 towing but I'm definately not as happy with this one as the '07, power and economy wise. H&S says that the newer one's (10 and newer) have different programming and that has been tougher to get more tunes for and when it comes to MPG, they wont even talk about it but they say it's because of the new ECM's.
Bottom line, leave it to the gubment to come up with a plan to help save the environment....... burn more fuel. I've heard good things about the new Fords as far as MPG's go, in stock form. I didn't have any concern on deleting mine and warranty, once you get rid of the EPA parts you have a Cummins, and your warranty will still cover things not directly related to the parts you deleted.
Then, at 107k miles I decided I would try a new one and picked up an '11. Brought it home and immediately deleted and tuned it exactly the same as the other one. Mileage prior to delete's was again around 13 empty but after deleted I only gained 2 mpg at best, it has been getting better since it hit 30-35k miles and now with about 45k I'm getting around 18 empty. I'm hoping for 12 towing but I'm definately not as happy with this one as the '07, power and economy wise. H&S says that the newer one's (10 and newer) have different programming and that has been tougher to get more tunes for and when it comes to MPG, they wont even talk about it but they say it's because of the new ECM's.
Bottom line, leave it to the gubment to come up with a plan to help save the environment....... burn more fuel. I've heard good things about the new Fords as far as MPG's go, in stock form. I didn't have any concern on deleting mine and warranty, once you get rid of the EPA parts you have a Cummins, and your warranty will still cover things not directly related to the parts you deleted.