The Hayabusa is a very fast bike... but depends on your
definition of fast, fast in a straight line, yes it is, bike
shootouts are usually done at unused airport runways... don't see
too many roads like that in Singapore or anyweher else though, the
Zx12r is also another monster, but all that power must be able to
be controlled by the rider.
I feel the Zx12r has better handling than the Hayabusa, due to
weight distribution and the shorter wheelbase i.e. it WILL corner
better, and the bike is more nimble.
Therefore straight speed fast, I agree would be the busa, but
overall fast, in my opinion would be the ZX.