Histograms of the plasma beta values for all gas cells upstream at t = 0 Myr (dashed) and in the shock-injected region at t = 250 Myr (solid) for our Mach 3 fiducial simulation, weighted by the cell volume. The distribution initially peaks at 100 (marked by a dotted, grey line). Amplification downstream is able to increase the magnetic field pressure up to ∼10% of the gas pressure in a fraction of the cells.