Don't know if this has been discussed yet so don't flame but IMO the best way to get off S. Boost is to do it with a neutral jump punch while your in combo and there in trance. If you do back 3 1/2 into 212 trance, throw out another trace for meter then hit them with a neutral jump punch, as you can see they go flying down across screen, once there down you have a great oppertunity to throw out an EX S. Boost if your health is low or what not to build health. Now if you do it to early while they're still downed it wont register and wont work. You have to time it just right so you have the advantage to get it off before they can get up and disrupt. Now I think the only way this move is legit is when your down in health and have meter to throw out an EX Boost to give you health. If you have health advantage obviously best is to end your combo in skydrop and do rune trap or resets. Play around with it.