  The NEUT intranuclear cascade model is described and fit to a large body of
\pipm--nucleus scattering data. Methods are developed to deal with deficiencies
in the available historical data, and robust uncertainty estimates are
produced. The results are compared to a variety of simulation packages, and the
data itself. This work provides a method for tuning Final State Interaction
models, which are of particular interest to neutrino experiments that operate
in the few-GeV energy region, and provides results which can be used directly
by the T2K and Super-Kamiokande collaborations, for whom NEUT is the primary
simulation package.
