What I could add to it is that palming is different from one guitar to another. You really need to experiment here but depending on how your bridge is, you'll have to place your hand on different position.
Usually, your chords will ring more the closest to the bridge you mute. Try it, place your hand and mute just before the bridge, then hit an Em chord a few times. Now place your hand between your neck and bridge pickup, now hit the Em again. Doesn`t sound the same right?
I'll give you that muting while your hand is between both pickups is not really effective lol but it`s only so you understand palm muting. The farther from the bridge you mute, the fastest your sound will die.
On my SG for exemple, I have to place my muting hand as far as possible to get the best sound. Otherwise the sound dies too fast and I don`t really like that :)
