stepper torque.....please help

i wanted to ask you all something .....i have 3- 305 oz-in motors
@4.5A per phase and 2Vdc ,using a 28 Vdc/12 A power supply,direct
drive config.. i was thinking about going with an "FET-3" 3 axis
unipolar controller rated up to 15A per phase with proper cooling
from stepperworld.com (only 135$ compared to gecko's at 114$ each)
(are the FET-3's any good?).....being that the rated torque of the
motors are for bipolar parallel, what would the approximate torque
drop be when hooking them up to a unipolar controller in parallel??
and is it going to hurt these motors using this power supply at this
amperage? the capacitors that i choose will reduce the current to
the motors?? or the voltage?? or both???

thanks for your time and answers.