I know getting a reply to this post is a long shot.

I am a 3rd degree black belt in Tae Kwon Doe. Ever since they made Sparring a Olympic sport Iv'e been sparring my butt off. Any way, in sparring, you need powerful kicks. And you need tremendous speed.
This is what I want to gain-

Speed and power in the following kicks:

Roundhouse(you know, the twisting your hip and bending your leg.....pretty common)

Back Spinning Heal Kick(doing a full 360 withough leaving the ground, slanting your body down, to kick higher)

Most importantly

Back Kick(doing a 180 with or without leaving the ground, similar to side kick, turning your hips, extending your leg forward, bending your bottom portion back)

This kick is extremely powerful. I hope there are kick boxers, or other martial artists who can help me.

So How do I make these 3 kicks more powerful? And Faster?