  The JIMWLK framework offers a powerful tool to calculate the energy
dependence of QCD observables at high energies. Despite a growing number of
observables considered for phenomenological analysis, few features of JIMWLK
evolution beyond its evolution speed are yet well constrained by experiment. We
argue that meson production cross-sections have the potential to provide
qualitatively new insights and allow to address issues both beyond the
large-N_c limit and at higher twist. These cross-sections generically contain
four point functions whose evolution is shown to follow from the JIMWLK
framework. The Gaussian truncation is used to provide an efficient and
practical means of calculating the evolution of four point correlators beyond
the large-N_c limit.
