It would be the perk points maker. 
Even the Ki-43-III would probably have an ENY of 30 or so. If a fighters gets slow and gets a Ki043 on him, he'd better have altitude to blow to get clear or he probably isn't.
The Mosquito Mk VI is much faster than the Ki-43, yet I know of at least one Mosquito VI that was shot down over Burma by a Ki-43 after the Mossie tried to fight.