$R_S$ (at midrapidity) of $\pi^-$ source from central Pb+Pb collisions at SPS energies. The data (solid stars) are from the NA49 Collaboration [@Alt:2007uj]. The pure cascade calculation is depicted by lines while the hybrid model calculations with different EoS (HG, BM and CH) are depicted by dashed lines with open symbols. As was shown before, the cascade calculation gives a fairly good result of the $k_T$ dependence of $R_L$ and $R_S$ values except at quite small $k_T$, while for $R_O$, it is slightly larger than data at large $k_T$. In contrast, the hybrid model calculations show large HBT (for all employed EoS, but to a varying degree) in all directions, especially in the longitudinal direction. The HG and CH are moderately increased and lead to very similar results for all three directions. The large latent heat in the bag model leads to a further strong increase in the longitudinal direction and in the transverse direction at large $k_T$. This increase in the BM mode becomes more pronounced at higher beam energies. At first glance, this result might be surprising because at least in the transverse direction one would expect a faster expansion including a hydrodynamic evolution. On the other hand, 