Modding the controller may produce no improvements if the system is BEMF limited already. In any case it will provide improvement only at low to mid speed, and it may reduce the reliability of the controller right into failure.
Exceeding the current ratings of the BMS will likely destroy it or cause it to shutdown.
Exceeding the current capacity of the cells in the battery will cause them to heat, fail early or underperform.
If your present system is fairly balanced it won't be easy to improve it as everything may need to change.
Making measurements may allow figuring out how much performance improvements are possible without doing them. It also may help predict where the stress and failure might occur, but there are enough unknowns that this is not certain.
You may need to add mechanical improvements to the system or suffer failures there as well. For example torque arms may require improvement.
If you embark on the hacking process you must be willing to suffer the failures, financial costs and unreliability. For a commuter these costs can be higher than expected - missing work, or an important meeting. One fellow was recently riding one of his ebikes and due to increased torque from a new motor, lack of torque arms and the nuts coming loose he broke the dropouts on his expensive new frame trying to not be late for an important meeting.
There are some folks experimenting with running two controllers in parallel with good results, which is interesting and somewhat surprising. If you added a second battery and a second controller you could increase the current and the range without overloading either controller, battery or BMS. Providing your controllers tolerate operating in parallel. However the same comments about BEMF still apply.
Doing some modelling with the ebikes.ca simulator may be the best first step, if your combination of components is in the model, or something close, you can see if the motor overheat is going to be a significant risk, and if increasing the current limit is going to help.
Increasing system voltage can make a big change in system performance, but again it depends where on the curve you are. It will increase the unloaded speed by the ratio of voltages, which isn't perhaps a huge change for a modest voltage boost. But motor power goes up with E squared, and without increasing battery current or controller current it goes up linearly. So if BEMF is limiting it can make a big difference. If current is limiting it will still make a linear improvement. Again, the simulator can be used to view these changes before making them. And understanding the simulator will be useful to help guide your next system design.
