A 6.4 is never a find! So do you wanna know why? During DPF regen raw fuel in pushed into the back two cylinders. It washes any oil off the cylinder walls and past the piston! It also cokes up and freezes the rings on the back two pistons. It then travels to the hot side of the turbo continuing to coke up the hot side of the turbo! Then to the DPF. Cant imagine why thats an issue ?. Remains a mystery why ford would do the exact same thing on the 6.7. Seems that a 9th injector would be ez. I think the fuel needs to be smokin hot to light the DPF. I know DPF delete> I did it with H&S. Smoke, Smoke and no fuel mileage change. Not worth the risk here in Cal....Took it all off

To me that is a short sighted view as I've learned more about these trucks. Removing the DPF is about an hour job and boom, you're done with regents forever. If your h&S was smoking you probably had the low boost setting ****ed up because mine never smokes unless I stand on it and I'm on 2. Plus you can very easily call gearhead and completely do away with smoke altogether.

I do understand your California emissions issues though......