It just crossed my mind that maybe the cam phasers are somehow involved. So I did a search under "cam phaser noise" and got all kinds of hits for modular engines. Apparently there's even a kit to deal with this.
'08 GT coupe, 5M, wheels, tires, pads, fluid, a few suspension mods . . . still almost stock height
'19 WRX, 6M (the "family sedan")
'01 Maxima 20AE, 5M (the spare and occasional winter driver)