  We calculate analytically the past asymptotic decay rates close to an initial
singularity in general G_0 spatially inhomogeneous perfect fluid models with an
effective equation of state which is stiff or ultra-stiff (i.e., $\gamma \ge
2$). These results are then supported by numerical simulations in a special
class of G_2 cosmological models. Our analysis confirms and extends the BKL
conjectures and lends support to recent isotropization results in cosmological
models of current interest (with $\gamma > 2$).
