We report on an ongoing study of the running coupling of SU(N) pure Yang-Mills
theory in the twisted gradient flow scheme (TGF). The study exploits the idea
that twisted boundary conditions reduce finite volume effects, leading to an
effective size in the twisted plane that combines the number of colours and the
torus period. We test this hypothesis by computing the TGF running coupling and
the SU(N) $\Lambda-$ parameter on asymmetric lattices of size $(NL)^2L^2$ for
various gauge groups. Finite volume effects are monitored by analyzing the
coupling in different planes and by comparing results at different number of
colours.