In reply to DreadyCraig: Hey man, I struggle with these too! What I can see from my dyno busting buddies is that there is a weightless point between the arm+leg movement where an explosive leg pop gets the extra height. Watch people doing it and you'll see the arms pull the body up then the legs fire the climber at the destination.
If there's any sideways travel, swinging your body to gather momentum really helps too.
Aim above the hold/s you are trying to get to, and try and 'catch' when weightless (at the apex of your flight).
Happy Popping!