Can't help you with the RAM sorry, I've only tested with Ballistix/Ballistix Tracers/Geil Black Dragon so far.
The VTT is much like any other voltage adjustment when you are overclocking. Just use what you need, start small and see if it makes a difference, and with each step, you will have to adjust the CPU GTL REF accordingly.
Saying that, you may not need any VTT/GTL adjustment at all - on my Wolfy and also my Q6600 G0 (both of which are just retail chips), neither of them needed any VTT increase or GTL REF tweakage to hit their max on air, just a small bump in vcore and NBcore.
Horses for courses really

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