Same as Fig. 6, but for observed galaxies in our sample. Critical radii are computed as a function of M_* using our fiducial model and the M+18 M_* − M₂₀₀ relation. Grey symbols denote all observed galaxies in our analysis while red and blue correspond to S and E galaxies, respectively, with stellar masses M_* = 10^{10.5 ± 0.1} M_⊙. It should be noted that the dynamical mass-to-light ratio increases with increasing galaxy size, at fixed M_*. The mass-to-light ratio ratios also increase, in general, with increasing galaxy stellar mass because massive ellipticals tend to have larger values of R_e/R_crit than less massive early-type systems. As for simulated ellipticals, the ‘tilt’ of the FP appears correlate strongly with galaxy size.