you should not change the dm threshold
it doesn't help you at all, because if you did that replay in regular dm threshold it wouldn't dm

Do /sm 1 for a speed metre with tells you how fast you're kick or punch is going to be the higher the speed metre is the more force you punch and kick that is how you dm

Try to hit the joints, hitting the joints gives you a better chance of dismembering that joint, like if you want to get a decap in multiplayer, you should go for the neck,harder to do, but more effective

multiplayer tip: they are many ways to get dismemberment for example if the torso joint is bent to the left and you kick from the right side and with the toess of ur leg there is a great change to split him in half (even in high dismemberment mods like abd)
here an example (replay).