i dont think the image in front of the booster really matters at all . in df i have so far pulled 6 exs and they all came from diffrent images on boosters . i got my first two df exs from the nidoking/ arbok booster, the third one from a tyranitar/Tropius booster, fourth and fifth one from a latias/ latios booster , sixth one from the salamance/dragonair booster. i went trought all the 4 diffrent booster images and pulled at least one ex from each image. so yeah mystery solved , the image does not matter . and i also dont think the weighing or bending of the boosters help in any way either . i have gone trought many booster and noticed that some are harder and some are softer and easier to bend . when i open them i have gotten completly diffrent results . ive opened hard boosters and pulled ex's , also opened soft boosters and pulled ex's . the hardness or softness dosent really matter at all. and if you really think about it ,do you really think that the machines they use to compress the matierial compresses everything equally the same . machines arent perfect and only approximate things so it isnt guaranteed that every single card would be exactly the same thickness .if the thicknes varies therefore the the weight of the cards varies making it very complicated to tell what type of card wiil be inside the booster.