Personally, I would avoid stim based fat loss products and stacks, because they can cause side effects, and they are not really selective in their catabolic action, so they will also burn off the lean muscle mass, not only fat. It does work, and some people don't even experience side effects, but the problem is that it is really hard to predict those, as it greatly depends on one's sensitivity to stims. If you want good fat loss properties, opt for compounds that were meant for fat loss and recomping at least, such as SARMS. Keep in mind that neither ephedrine, nor clenbuterol, were ever meant for fat loss, and these drugs were designed for a completely different purpose. Therefore, it can bring along many consequences. SARMS were specifically designed for fat loss and recomping, so you will have much better fat loss properties with no side effects. Additionally, they will only burn fat, and will maintain the lean mass. What's more, some SARMS will also increase the lean mass, and give you some very good benefits, such as: strength, endurance, recovery, mass gains, etc.