1. Expensive, and is federal not just CA. Who do you think imposed the emissions requirements on the mfgs? Some states are simply enforcing what has been the law for a long time.
2. It depends if you're willing to chance paying for a more expensive repair out of pocket since your warranty is going out the window.
3. Most likely not any major increases.
Bottom line, you bought a large truck and then lifted it sky high with big tires. What else were you expecting? If you are that concerned with mpgs then sell the truck and get something more economical and leave it stock. You're looking at maybe 5mpg difference and I doubt you'd even see that much. I'd leave it stock until the warranty is up since repairs to that engine are costly. Once the warranty is gone then I'd think about it. The biggest key to keeping the fuel numbers up on the 6.4L is keeping the rpms down and running as unloaded as possible. Both are hard to do with that engine, and your lift/tires makes it even harder. I've heard of guys getting near 20mpg in stock form with the dpf delete.
Last edited by powerstroke73; 05-30-2010 at 07:27 PM.