well I am of the opinion that if you are actually changing your oil as frequently as you should then there is no need to do the "top end oil change" I don't remember if he has you drain the high pressure oil rails or not and if you do then: What he fails to tell you is that in doing this you are introducing air into the high pressure oil system and air in a hydraulic system can and will cause excessive wear so while it does change the oil in the system you are creating wear in other locations until the air is worked out of the system.
If you are just changing the oil in the HP reservoir then great, it would be beneficial if you have very dirty oil in the truck because the oil was not changed. The reservoir & oil rails hold around 2.5 quarts (based on my injector replacement experience) when diluted in the 4 gallons of new oil this is not a significant portion for oil that is not filthy.
Keep in mind that this oil change is something that the 500k trucks he keeps referring to have never received. I'll stick with the regular oil drain & filter change.
The fuel fitting on the head that he is referring to is not going to be a great restriction until you are running very high horsepower with large volume injectors. A bit of quick math for you based on stage one injectors (160CC)
But first a quick metric system refesher
mL - milliliter
CC - Cubic Centimeter
µL - microliter
1 mL = 1 CC
1 mL = 1000 µL
160cc (milliliter) injectors refer to the average volume shot from a single injector in 1000 shots at maximum flow. This can also be stated as an injector that will shoot 160 cubic millimeters or Microliters of fuel.
ok given that you are at WOT turning the engine at redline of 3500 RPM the each injector will be firing 1750 times/min
1750 X 4 X 160 = 1,120,000 microliters of fuel per minute needed in each head (this is why the 4 injectors)
1,120,000 µl = 1120 mL/min
To convert this to a number that is a bit more common numbers the fuel required is 12oz (coke can) every 19 seconds to each head. The fuel is under 40-60 psi as it goes through the "restriction" which without doing the fluid dynamics calculations the existing 1/8" diameter holes (4 of them) I will say that there is plenty of flow in stock configuration, not to mention the impact of a 1/4" hole on structural integrity of the bolt that is not much larger.