ritalin is a mild uncomfortable tweak;
a good dose of adderall is like a higher level of tweak; a level i like to refer to as being "gacked"

in my circles,
tweaking is like "oh look at steve over there taking apart the VCR to see how it works inside, he's totally tweaked"
gacked is like "dude, steve is so gacked out right now he can barely talk, he's just sitting there with his eyes wide open bulging out of his skull"