My instructor says to things about kihaping. One- it gives you extra power and two: it puts the fear of God into your opponent. I was taught to kihap as i do my technique, but I see that others schools yell at different times such as before or after the technique. I was just wondering which time you were taught to kihap?

At the time of impact ... whether I making the impact or taking the impact.

I don't do it because it gives me more power or to put the fear of God into my opponent. I do it because it is an effective technique for focusing. When taking an impact, by ki-happing I can focus on breathing as well as tightening of my abs thus reducing the impact. When making an impact by ki-happing I can also focus on the breathing as well as the strike. It is also an effective way of focusing and believing in what you are doing.

It's also a good little exercise for confidence building

We kihap with a sharp exhalation, so no shout or cry. Like Dereck I have always been taught that it should be done at the moment of impact and that it prepares your own abdominals for possible contact as well as adding focus, timing and power.

i was taught to shout at the time of impact, however i don't!!! i like to hear the sound of the clean hit and the sound of my GI hitting the air.

There really isn't a golden rule with this, as with everything.
What I do though, is, like most others, yell/exhale at the moment of impact, or a few seconds before, because, with a confident fighter, a good yell can go a very long way.
It also helps build confidence – when I first started TKD at 17, I was pretty shy. After a few months of taking classes, my confidence was increased 10,000%. The yelling really does help.

Did anyone every hear the Lopez sister do her kihap?

Monica seles is compared with lopez nothing