Quite right. Our in-game model is an example of what the Japanese could actually field in battle. At first, at least. Ours is one of the earlier batches that could produce full power and weren't falling from the skies. Later versions were so underpowered and had such poor fuel quality that going back to an obsolete engine mounted to a Ki-61 airframe actually outperformed it significantly.
Our first version didn't even have WEP. That was an interesting airframe and IMO I liked it a little more. It had more elegance to it. However, somebody found actual documents from the wartime era allowing WEP use for short durations. That's how we have our current Ki-84's WEP. It really turns it into a killer airframe.
You will find our off-wep FTH is about 21k-21.5k, but with WEP we find our top speed around 18k.
A6M5b for comparison.
