Your stock X6 is now giving around 43kcd
I have two realistic suggestions for modifying it, starting from simplest:
1) De-dome the current emitter (very easy, see here)
- that should about double the reading = around 80-90kcd
2) Swap the emitter to a de-domed XM-L2 with SinkPad (practically overdriving the XM-L2 with stock driver)
- should give you over 200kcd