stimulants are anxiogenic but there's no doubt they make people extremely talkative. sometimes i find myself looking for someone to talk to around the house if i'm up late and everyone is sleeping. there's a distinct possibility it could raise your anxiety, but it most probably will extend your speech by a solid 2-3 hours if no one tells you to simmer down. the beautiful part about it is you always find yourself saying the right things, and grabbing the correct information from your brain. you also become extremely articulate.
personally i find it a great tool for anything that has to do with school. i would recommend you give it a trial run at home first so you get a little idea of how these drugs work and more importantly, how they affect you. maybe do a mock run of your speech. good luck.
Stimulants like amphetamines produce a sense of well being. The amelioration of anxiety is a by product of feeling good. Amphetamines or cocaine or other CNS stimulants will induce a sense of well being such as to feel only the good effects
during the early stages of use; after that, the sense of well being decreases such that in proportion to the side effects, you will begin to notice an "edge."
I'm very well versed with the effects of Adderall and Dexedrine. I haven't fucked with Vyanase; as I understand it, the drug is metabolized and it cleaves off something (attached, purposely, to reduce abuse and get a patent? = $$$ ?) and voila, the D-amp is freed to do its work. Anyhow, I haven't taken it.
Long story short. Do not try something volatile for the first time in a situation that's already making you anxious. Second, if you are going to do it, take a gentle small dose. You'll feel a mild mood lift -- certainly, it would be enough to provide only positive effects. For example, I would recommend a first time user of Adderall or Dexedrine take 5 mg for a speech. I would also advise to self-monitor for rambling and seeming out of character. I agree with everything Baooozs said, notwithstanding the clarification about stimulants mitigating anxiety. Even an experienced user can start babbling.
I find myself agreeing with OC80. A grain of benzodiazepines would make more sense. Failing that, a LOW dose, preferably after you've tried it once already, acclimating yourself to the effects somewhat, is what I would suggest. 5-10 mg will do it; make sure you look up the time for onset of effects. One other note, if you're going with a less sexy d-amp you should make sure you time the dose so you've plateaued. You'll be better grounded.
Remember, this can be done without any drugs if you have the will. It's been demonstrated in quality scientific studies, one which I've personally read, that people pay less attention to you than what you would estimate to be the case. Everybody got their own thing. They don't really have time to fixate on you.