Hmmm??? Power shift from my understanding is WOT shifting. But you do use the clutch. Of course some kind of rev limiter is generally a good idea.
Maybe you are thinking of shifting a dog box like they use for Nascar? That shift can be done without a clutch, but it requires a quick power unload to free the load on the dogs. In fact shifting a dog box like a synchro box can cause damage, since the dogs do not like being engaged slowly.
