Top panels: [O III] and Hα velocity maps showing fifth (first row) and ninety-fifth (second row) velocity percentiles of the HV components in MR 2251−178. The dashed circles show the maximum R_out adopted for the calculation of the momentum boost. The green filled circles indicate the size of the PSF halo, which is markedly smaller than the spatial extent of the data. Bottom panels: same as for PG 1126−041. The green dashed circle in the Hα panel shows the outflow radius corrected for the effect of the PSF.