Does flexible exchange rates and an open economy magnify the effects of monetary policy?

i would guess no, because if you were conducting monetary policy in a closed system you would have much better control on its outcome. In an open system there would be leakages as money could flow outside of borders and governments with flexible rates would still be at the mercy of the international system. Example: What if the U.S. and the EU both decided to pursue a very loose monetary policy? The U.S. was desperately trying to weaken the dollar versus the Euro but the effect would be stymied because of what the other party was doing.