How can I speed up travel on this Boxford router? What new stepper motors to get?

[JAZZCNC]

Well first things first don't go buying any kits as chances are they will be wrong for your needs. It's the most common mistake made by new users.

The Motors on the larger machine where 23's however doesn't matter performance will still increase with more voltage.
What's important is you don't run the current too much higher than the motors rating. Increasing voltage will increase the speed and to some degree torque however it will also increase heat and it's this heat that leads to iron losses in the motor which then lowers performance/life expectancy. However Steppers are very robust things so you won't kill one very easily, they are also often over specified for the machine which will 99% be the case here.

So we can safely say that because the drives are rated max 2A then the motors will be close to this so working on setting of 2A on the drive will be close enough and not cause any damage.
Voltage is mainly calculated using the inductance of the motor which in this case we don't have and can vary widly depending on motor quality and wiring type/numbers. ie: Bi-polar Series or parallel. 4, 6 or 8 wires. However if we use typical voltage rating given for larger nema 17 motor of say 2.5v and use the rule of thumb method of calculating voltage which is 20 x rated voltage it gives 20 x 2.5 =50Vdc.

So your safely within the motors ratings on voltage with 44Vdc and provided the current rating on drive is close to the motors rating you'll not hurt the motors. Also modern Digital drives run motors much cooler than Old analog technology which helps motor cooling.

Now your probably wondering "Well if that's that case why didn't Boxford do that.?" It's simple they always de-rate to ensure reliabilty and since these machines where intended for schools speed wasn't great concern.
Modern drives are worlds apart from the ancient tech used in these machines so will happily run close to there max without any issues and with much greater performance.

The trick is getting the right drives and voltage supply then matching with good controller. This you won't find in Kit form.