  We discuss boosts in a deformed Minkowski space, i.e. a four-dimensional
space-time with metric coefficients depending on non-metric coordinates (in
particular on the energy). The general form of a boost in an arbitrary
direction is derived in the case of space anisotropy. Two maximal 3-vector
velocities are mathematically possible, an isotropic and an anisotropic one.
However, only the anisotropic velocity has physical meaning, being invariant
indeed under deformed boosts.
