The deflagration model is developed for a physically substantiated situation when free pions are radiated directly from a time-like hypersurface formed by a rarefaction shock wave. It is shown that the shock front and pion collective flow velocities are enhanced in this approach as compared to the standard deflagration model. Exotic regimes are also possible. The stability conditions are investigated and analytic solutions are found. We calculate the pion transverse momentum spectra in ultra-relativistic nuclear collisions and indicate their behavior in the region 0.2 GeV/c<p⊥<1 Gev/c. The spectra are essentially different in this region depending on whether or not longitudinal collective flows are in a mixed phase.