I'll ask a few rhetorical questions, and you mull over the answers ...
1) How does one accurately judge "noise" percieved at the human ear? Did you use any SPLM (sound pressure/level meter) or or other auditory calibrated device?
2) How does one accurately judge the rate of revving? One would need to be able to definitively develope a relationship between the accel pedal and the rate of vehicle movement (or revving in park) if accurate measurements were to be taken.
3) HEUI gets blamed for so much stuff; it's tiresome. Did you know that in a 7.3L PSD, the HPOP oil only lifts the pintle for the injection event, and a spring closes it? (As opposed to the 6.0L PSD, which uses oil for both open and close cycles). So, would the oil only get 1/2 credit or 1/2 blame in a 7.3L PSD?
4) You indicate this is a "new" 7.3L; how much experience do you have with this engine family, and this one unit in particular? Do you have a decent basis to make subjective observations?
Originally Posted By: matt711
I swear that the engine is quieter and seems to rev more quickly. Am I just imagining things?
Probably so. To prove it, you'd need a whole slew of accurate, dedicated equipment.
Or, the alternative would be to run a large series of trials back-to-back (30 or more), running short OCIs with both fluids, letting a trusted friend do your OCIs in a blind test and then note your "observations"; you'd need at least a 95% confidence level of correct assignment to make it believeable.
I don't doubt that you perceive it to be so, but that does not make it a reality. You may well be correct, but to convince me, you'd have to prove it, not just claim it. And I have serious doubts you'd have to overcome to change my mind.
I know I take the fun out of things, but I'm just "that guy" who relys on facts and data rather than subjective mythology.