I've taken some videos and they're uploading to YouTube. Should be viewable in just a bit. If anything, I notice the sound more after the engine temps come up. The cooler is definitely getting flow and 'working' as the engine temps are about 20F lower in any given situation now. You may also notice I have the Stillen power steering cooler installed. There is no association with steering input, so the steering cooler isn't related.
I'm wondering if I'm crazy or what. The sound seems to be more from the block/valvetrain than from anywhere near the cooler or lower by the oil pan. You'll notice it on the decel as the revs drop below 2k towards idle (but audible throughout the range).
I did have the engine oil on the high side, so I just removed about 300ml and it's just below the H hole now on the dipstick. No change in sounds though.
Hopefully this is a just case of hypochondria given my reading about all the oil-cooler debacles people have had.
In Car:
Outside car using a torque wrench to depress the accelerator!: