Effect of changing the correlation coefficient between halo spin and concentration r_λ − c (left) and the slope of the relation between the stellar angular momentum fraction and the stellar mass fraction s (right) on the correlation of the TF and MS residuals as a function of the radius where the TF velocity was measured. The grey dashed curve shows the data from the SPARC sample, while the different red curves are models with different values of such parameters. In both panels, the thick red curve is our fiducial model (shown also in Figs. 1 and 2) with r_λ − c = −0.4 and s = 0.4; while we fixed s = 0.4 in the left panel and r_λ − c = −0.4 in the right panel. The grey area marks the region where the predictions of our model are not reliable, since we do not include a bulge component in our galaxies.