AMBS.. they do give u the jitters, especially on an empty stomach. I've too it once at a club and gave me that boost but i just crashed afterwards several hours later.. was really tired. They really warp your energy levels down too... You guys should try Guarana. Herb like ephedra. It is in several energy drinks like Bawls (www.bawls.com) or Monster .. get the sugar free ones, they taste better for me atleast...