Hi guys, My spec's are

Motor
Nema 23 425oz model 23HS2430 3A
1.8 step angle
3 amp
2.1 phase resistance
9 phase induct
4 wire

Driver
DM542A
128 microstep
1 amp to 4.2 amp
18 to 50 VDC
I am trying to increase my speed rotation. I get only 80rpm for now. What should i do to increase my rotation speed?