How high can a typical BBM HR setup spin before the extra weight of the roller lifters starts to become a limitation? I know some people have used (made?) restricted plunger-travel HRs to squeeze out more RPM. But that's not the "normal" build, is it?

As I've gone faster over the years, my required RPM ceiling has also been raised quite a bit... 5800... 6400... 7000... 7200. How far up my incremental RPM steps could a HR have taken me?