B16A2 - 10.000 Rpm?
 

One Honda with an B16A2 unit , reaching around 10.000 rpm at Hungaroring Drag Racing

Not exactly that big of a deal, the F20 engines did that in stock form in the initial S2000 models.

Well its not dificult to reach 9000 (as S2000 did, not 10000?), but every 100 rpm more is a nightmare to reach. So 10000 rpm is not something you see "everyday". Stock B16 has a redline at 8200rpm. Even finding some cams that produce power at that rpm is difficult.

I think reaching 9000 rpm in a B16 is not an difficult job, you can do that with only a few modifications, but 10000 is another level of preparation, everything has to be nicely balanced, an, like ru7 told, finding a cam that brings power until that rpm is difficult....