Actually, the thing that jumps out at me is the lack of performance boost the 1.98 ata rating seems to give over the 1.8 if the tests are correct.
Atmospheric conditions, lack or inclusion of wheel well doors, ect, could throw off a flight test by a few mph either way, and I think it is almost impossible to nail down that precisely.
In any case, I dunno if +/- 5 mph (447 vs 452) is worth getting too excited about. I could see it if the K-4 was way over the top in terms of specs, but it doesnt look like it is.
They could model it do 447 tops, and nobody would ever know it unless you told them.