I would say that the M5 in general is phenomenally engineered, but that a few items found in the engine package are not necessarily ready for massive (200hp+) gains over the original power output.
With that being said, a few clarifying statements:
-The above is only a preliminary impression. More analysis is necessary before we can make specific statements.
-BMW has done an excellent job in engineering the drivetrain around their target power level. The S63tu engine is incredibly capable and seems to be extremely robust when used as BMW intended i.e. when making the original ~530 wheel horsepower, or even 100-200 horsepower above factory. I believe that M5 owners will enjoy excellent longevity and that the S63tu will prove to be a very robust power unit.
-Our goal is to exceed the 1,000 horsepower mark, so when we consider the strength of components we are looking at power outputs well beyond what the factory intended. We hope to find the ultimate weak points of the S63tu, so that M5 owners do not have to.