One very common problem with the 6.4L platform built into the Super Duty line of Fords is the failure and breaking of the up-pipes located on the rear of the engine. For those that do not know, the up-pipes are the connecting pipes that go from the each exhaust manifold to the turbo as well as a crossover installed that heads over to the EGR cooler. That is a total of 3 pipes, 11 attaching bolts, 6 studs and nuts. Sounds easy, right?
This common problem has a very common symptom. If the up-pipes are damaged, broken, cracked you will be able to hear an audible leak. It will sound like an air leak while accelerating. Some people may describe it as a hiss. It will definitely be lacking power and generally will not build boost as quickly or max out as much as before.
It is a long drawn out process to install these pipes correctly. There is a torque procedure and sequence that must be followed or damage to the new up-pipes will result. If you are wanting to remove the EGR coolers, now is the time to replace these pipes with the deleted kit. Of course, that's illegal for use on the highways. I have listed and linked the pipes you will need for standard replacement and for EGR deletion.
To change the up-pipes, the cab will need (or I should say, should be) removed. You can find steps for this process by reading my other article Cab removal of the 6.4L Power Stroke.
This article is incomplete. I will get the torque sequence put up here in a few days for those interested.