A word of caution about vasodilators: I've seen them touted more and more frequently by nootropics enthusiasts, as though they're completely harmless. This is not necessarily true.
Blood pressure is a very meticulously regulated process in the body, with countless chemicals, hormones, and other endogenous signals in the mix. It's entirely possible, if uncommon, to overdose when self-administering vasodilating drugs. A lot of vasodilators work by ionically tweaking the fluid retention of the kidneys, which, if thrown out of whack, can lead to all sorts of not-so-fun problems.
In general, be careful when messing with your blood vessels, or with any drugs that change the ionic balance of your bloodstream.
The other thing I'd say is TANSTAAFL. Generally speaking, when you're upregulating one process or chemical in the body, you're downregulating another process or chemical. If you're not sure what's being ramped up, and what's being ramped down -- or, even scarier, if science doesn't quite know yet -- then proceed with a tiny bit of caution.
I don't mean to dump cold water on the idea of nootropics. Some of them seem pretty harmless. Some of them may indeed have a net benefit. Others...perhaps, but the jury's still out. In the meantime, I guess I am hesitant to treat my body like a lab experiment. Especially when there are so many proven, healthy, effective ways to enhance cognition. Such as exercise and study.