Why did you open a second thread with the same question?

If you want to get some feedback here, try to write/explain better and more detailed what you have.

What means 189nm? nm is the symbol for nanometre. You wanted to say Nm? Then I doubt there are 189...
What steps have you set to 3200? Are you talking about microstepping? Are you setting them in a drive unit? Has this drive unit a name/model number?
Your 800 mm/sec does not look fast... What software are you using? have you set the unit correctly? What is your acceleration?

You are asking about changing the motor but you did not tell us what drives you have (current and voltage ratings) and what is your supply voltage. Stepper torque at high rpm highly depends on the voltage and drive quality.