Will probably have to make a suggestion thread. The way OVBs and OBBs work (I think lol someone else may have to answer this one) is that it's not a percent chance of getting an item from it. It's more like reaching your hand into a box of items (in this case, the list of items an OVB and OBB can give) and you picking a random one. The only way to probably influence the drop ratio, is to remove items that the boxes can give from the list.
