Leon, I dunno about some engines as pretty much all engines these days have hydraulic lifters, including RE now
The rev limiter on the EFI cuts the sparks at 5500rpm. The Power Commander can be used to extend it higher, I've used its 'Rev Xtend' function to set it to 6000rpm because it was cutting well below 5400 in lower gears (the PCV imposes a lower rev limit), but to be honest the motor won't pull beyond 5000 in top anyway. An absolute red line of 6800 seems reasonable, but the EFI won't rev that high.
I'm not convinced the PCV Rev-Xtend allows it to rev higher than the ECU limit but it did seem to be imposing a lower rev limit and was becoming a nuisance around 4800-5100 under acceleration through the gears (I have a tacho). The ECU limit of 5500rpm seems to be a fixed point, I have simply moved the PCV limit up out of the way. I don't normally rev it that high but I don't like having artificial limits imposed.
Something I've noticed is that if you do rev this engine higher, it becomes more willing to rev higher. Final stages of running-in.
Regarding oil getting to the hydraulic lifters, the later EFI motors have colossal oil pumps that irrigate the motor at several times the rate of the earlier engines. Oil would only be lost from a lifter left in compression i.e. with the valve open, and then only for a few strokes whilst it starts up.
