its standalone ecu
hope u understand computers
ok like this
ur stock ecu is not programmable, no modifications can be done on the ECU , unless u play with the electronic chip there.
standalone ecu , is to fit any cars according to the wiring, then program A-Z all the settings u need , only modded cars take this option , y must a stock car which settings need no modifications take a programable ecu like haltech/microtech :)
it will UP ur hp IF and only if , ur settings are no longer cope with stock ecu cos u modded ur car.