Comparison in density profiles of 1D simulations similar to the fiducial case CygX3. Everything is the same as in Fig. C.4, with the exception of the adiabatic index Γ. Little effects are observable on the jet head (the thin high-density shell) propagation when Γ is varied, but choosing Γ = 5/3 results in a more advanced front shock by 25% in the Newtonian case and 16% in the relativistic one. This is caused by a stronger cooling of the shocked gas due to higher densities.