Streamlight Survivor Modding, ideas needed

I'm running through ideas on modifying this SL Survivor that I have. Currently it houses an unknown bin factory XPE and runs at 150ma low/610ma high. My goal is to have the high be at 1A.

Originally I was planning on swapping a 5500k cool white R5 XPE for the added brightness (I want neutral but no good bins) but I want to see if I can push it harder. The circuit board looks fairly advanced, so I was thinking about ripping out the entire circuit and wiring in a board. This board was what I wanted to run, with a reverse clicky for mode switching. Power supply will be 4xNIMH AA in serial.



Ideas?

Looks to be a sort of the PITA to swap in a board without some fab work. Anyone familiar with circuits?? I'm want to try to remove a resistor to up the output of this board.