L-Tyrosine? I seem to have more mental energy, focus...

Recently I started taking L-Tyrosine supplements. L-Tyrosine is said to boost the production of the neurotransmitters: Dopamine & Norepinephrine. These are what ADD/ADHD medications like Adderall Stimulate the abundance of in the brain. Though Adderall doesn't actual make these transmitters they help raise the levels. You can wiki more about it. Anyway, I've been taking L-Tyrosine for a few days now and noticed that I seem to have more mental energy, focus, and all around good sensation in my body. I have wondered if this was a Placebo Effect but it's too noticeable to be ignored. I was wondering if anyone else has tried L-Tyrosine tables/supplements and what your results were/are? PS I may have undiagnosed ADD/ADHD but like most people these days I'm interested in that extra mental energy and focus. For a very long time I've been hooked on caffeine but with sad results. Coffee & other energy drinks help a little in small amounts but often leaves me feeling jittery, nervous, and unfocused despite all the energy. It's seems to cause ADD/ADHD in even people that don't have an Attention Deficit (not just me). Sure your mind races but it's unfocused and even if you do force yourself to focus it's still hard to study. So I like most people are becoming ever discouraged about caffeine and are turning towards alternatives. I know L-Tyrosine alone may not be enough for some people. But I'd like to hear what your opinion(s) are of this product. Also any other supplements out there that aid in mental & physical energy (CNS energy). OH, and PSS I've tried Focus Factor with little to no results.