I have been using various (I have tried about 90% of all commercially available nootropics) noots for more than 5 years so I have tons of experience with them.
I've posted some info about some of the most popular ones in MDMA forums and will repost it here if anyone is interested:
Besides enhancing the roll and reducing neurotoxicity nootropics might give you the worst headache of your life lasting for hours, ruin your trip, cause lots of anxiety and actually be the cause of neurotoxicity if improperly combined with powerful psychoactive drugs.
I recommend to get the feel for nootropics you choose to use by themselves first to see how your body-brain-mind-emotions react to them. And when combining with psychoactives, always start with lower dosage for noots!
Of all the nootropics and smarts to go with MDMA and psychedelics I'd recommend:
Oxyracetam (increases visual effects, adds to hypomania and sense of well-being),
Aniracetam (increases visual effects, increases auditory effects, adds to sense of well-being),
Piracetam (increases visual effects, adds to hypomania and sense of well-being),
Phenibut (adds to hypomania and sense of well-being, relaxes),
Agmatine (adds to sense of well-being, relaxes, soothes).
These three are pretty good by themselves and could be used with psychedelics and molly but with more caution than the other noots and with a lot smaller amounts if taking with psychedelics:
Huperzine A (increases visual effects, increases dreaming and imagination),
Phenylpiracetam (greatly ad ds to hypomania and sense of well-being, speedy),
Pramiracetam (greatly adds to hypomania and greatly increases memory recollection).
Magnesium is not a nootropic in a classical way but still considered by some and it is mild vasodilator and a weak NMDA antagonist (the most famous NMDA-antagonist is Ketamine), I find it beneficial before, during and after trips.
Noopept is too powerful even by itself and may cause a really bad headache for hours when mixed with psychs, stims or molly. I suggest to never mix Noopept with any psychoactives. It is pretty effective in what it's doing though and I consider it to be the most efficient nootropic in terms of cost/effect.
Sunifiram is another very effective noot, with speedy and clear effects, much more effective than Noopept, but very unresearched and pricey IMO. I would never recommend combining Sunifiram with psychedelics.
Tianeptine is not a nootropic, it is an atypical anti-depressant, so it has to be treated as such, like a prescription drug. It will increase effects of lots of drugs but I have a feeling that it will not be healthy. I advise not to mix Tianeptine with psychedelics.
As for dosages, it will vary on what combination you're taking.
Be safe!