Stu, at 6000rpm you have 7.2ms of open inlet valve with a 260deg cam NOT 19ms.

Also I disagree about your comment about needing exponentially bigger injector as rpm rises.

Injector size is totally dependant on number of cylinders and bhp alone, rpm does not play any significant part.

This is because to obtain the same power as rpm rises the torque decreases with the same relationship. Since the torque is falling (i.e. the bmep and hence air consumption) so does the need for fuel in maintaining the correct AFR.

In Laymans terms the cylinder specific air consumption for 600bhp @ 9000rpm is much lower than an engine making 600bhp@6000rpm, though they will both require the SAME size injector!!