Reg pressure

You increase the reg pressure to have more power ... you increase the hammer spring tension (HST) to max out that power, meaning opening the valve (since you have more pressure you need more force to open the seal on the valve)

When you reach a point that you increase reg pressure and HST but there is no increase of velocity, there is the point when you need a hammer weight (with pretension) so you can hit the valve harder in order to open it fully.

On impact usually that happens on regs pressures over 150bar +- or lower if you use larger ValveSeats, the chony is the witness of it.