The current you get depends on the torque (accelerator pedal) demand, but also on how the controller converts that torque demand to actual current demand, any operating limits that have been set, etc. To find out the controller's settings, you will need to connect to it via a programmer and go through all the relevant pararmeters to find out where the limitation is.
All the above assumes that the controller is capable of the 400 A that you are hoping for. If that's beyond its physical limits, then of course you can only get what it was built to deliver.
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