I have a book from osprey called aicraft of the aces legends of world war two. the last chapter is called master falcon. It talks about the kawasaki ki100. In it a force of 24 ki100's interceptid 200 p-51s. In the end the japs shoot down 11 p-51s and only lost 3 planes in return. The story is told from the perspective of a japenise pilot and claims that it was easy for them to shoot the mustangs down. I belive the mustang had a 60 mph speed advantige over the ki100.

I think that is proof that the ki100 is one of if not the best dogfighter of world war two.
Here is a link for the ki100
Kawasaki Ki-100 - Wikipedia, the free encyclopedia