The 2D waves testcase results are presented in the next plot.
The effect of the ajustment for the 2D waves is presented in the following plots.
We conclude that the major difficulty with the simulations are with long wavelength modes, as exemplified with from the series of snapshots in the next Figure.
The long wavelength error will eventually cause a either superluminal instability or a breakdown in the spacelike character of the Cauchy hypersurface.