  We study the evolution of the non-linear curvature perturbation during
perturbative reheating, and hence how observables evolve to their final values
which we may compare against observations. Our study includes the evolution of
the two trispectrum parameters, $\gnl$ and $\taunl$, as well as the scale
dependence of both $\fnl$ and $\taunl$. In general the evolution is significant
and must be taken into account, which means that models of multifield inflation
cannot be compared to observations without specifying how the subsequent
reheating takes place. If the trispectrum is large at the end of inflation, it
normally remains large at the end of reheating. In the classes of models we
study, it is very hard to generate $\taunl\gg\fnl^2$, regardless of the decay
rates of the fields. Similarly, for the classes of models in which
$\gnl\simeq\taunl$ during slow--roll inflation, we find the relation typically
remains valid during reheating. Therefore it is possible to observationally
test such classes of models without specifying the parameters of reheating,
even though the individual observables are sensitive to the details of
reheating. It is hard to generate an observably large $\gnl$ however. The
runnings, $\nfnl$ and $\ntaunl$, tend to satisfy a consistency relation
$\ntaunl=(3/2)\nfnl$, but are in general too small to be observed for the class
of models considered regardless of reheating timescale.
