Recent molecular dynamics (MD) studies have shown that the high-speed jet impact of graphite flakes on a diamond substrate can cause exfoliation to yield few-layer and multi-layer graphene. The method has the potential to be scaled up for mass production as the estimated yield rate is high. This study focuses on improving the high-speed impact-induced exfoliation process by introducing nanoscale rectangular groove texture on the diamond substrate. MD simulations are performed to study the effect of various parameters like impact velocity, impact angle, orientation of the graphite flake and step size of the groove edges on the extent of exfoliation. Using these simulations, it is shown here that the energy loss due to impact decreases as these grooves improve the process by improving the exfoliation mechanism. The groove edge acts as a cutting edge to support the exfoliation process, making the layers shear/cleave, and utilising the impact force to break the interlayer bonds. The range of optimal values of impact angle and orientation of the graphite flakes are broadened which in turn enhances the probability of exfoliation that leads to higher graphene yields. The minimum impact velocity required for exfoliation is also reduced, thereby improving the yield per unit power of the process to three times. These results promise an increase in the output at a lower impact velocity which helps the process scale up to mass production and produce large quantity of graphene at a lower cost.