Since my request has been fulfilled - I shall oblige. Thank you - Tamisha was ecstatic.
This whole debate can be boiled quite succinctly down into two issues:
1) Does this thing actually improve performance? Cass said he has evidence to support that it does with improvement in several test trucks as well as years of experience with these trucks. I'm inclined to give him the benefit of the doubt - its no secret that we've known each other for years and consider each other friends. I eagerly await the presentation of said evidence with the rest of you.
2) How does it work? I don't have a a concrete answer on that - but I do have theories which I will outline in a moment. First I'll post a paraphrase of what I told Cass "I know for a fact its not that bull**** you posted on the FB ad" ..... Maybe that isn't actually paraphrasing.... LOL
Theory 1: Firstly - we need to dispel a myth that I have seen repeated in this thread numerous times. Engine oil is compressible. That is a FACT. This is especially true when it comes to aerated oil which is pretty much the only thing that exists in a 7.3L Powerstroke. These rails take up a known volume of the factory "reservoir" giving less volume to be compressed. This could be a method of stabilizing the pressure.
Theory 2: This would be my front runner theory, but its more of an educated guess. These inserts actually dampen the pressure waves that are taking place within the oil rail. Fluid harmonics in a transient flow like this are a PITA. By inserting this device into the oil rail its giving a new surface for the pressure waves mostly being generated by the starting and stopping of oil flow at each individual injector a new surface to bounce off of and dissipate.
Theory 3: I don't have one.... but that doesn't mean there isn't yet another undiscovered mode where this device could improve the rails. If you have theory where this might work - please share.
In any case - if the tech performs as advertised regardless of the the actual physics behind the why it works - that might be what truly matters. While the fluid mechanics of the initial theory that lead FFD down the path to develop this might be fundamentally flawed, it is quite possible that they have stumbled onto something unique and quite worthy of the small price they are asking (compared to anything else for these engines). I think we often forget that sometimes some great things are discovered entirely by accident. Corn Flakes, Teflon, Post-It Notes (the adhesive), silly putty, etc.... were all things created in the pursuit of something else.
That is my take on this. Does it work? Maybe. How does it work? Not as its advertised currently.