  Based on hep-ph/0510121, we discuss further the numerical study of classical
SU(2) 3+1-D Yang-Mills equations for matter produced in a high energy heavy ion
collision. The growth of the amplitude of fluctuations as $\exp{(\Gamma
\sqrt{g^2\mu \tau})}$ (where $g^2\mu$ is a scale arising from the saturation of
gluons in the nuclear wavefunction) is shown to be robust over a wide range of
initial amplitudes that violate boost invariance. We argue that this growth is
due to a non-Abelian Weibel instability, the scale of which is set by a
dynamically generated plasmon mass. We find good agreement when we relate
$\Gamma$ to the prediction from kinetic theory.
