I have been working a bit on this light to make it into a gift for a friend of mine, nothing like a OL make-over, but I'll share some findings:
stock current: 2 amps, I used a freshly charged CGR18650CH Panasonic IMR battery for all current measurements.
there are 8 x 1.5 ohm resistors on the driver, I paralleled another 5 x 1 ohm resisitors, the current went up to 2.5 amps
I put copper braid through the tail spring and contact board spring. the current went up to 3.0 amps
I decided now to just skip the current limiting resistors, that is easy done by moving the led-plus wire to the convenient blob (also labelled out +) that is to the bottom right of the original connection (I guess they made that one especially for me):
the current went up to 3.5 amps. (I'm beginning to like this simple driver, am I the only one?)
The led board started smoking at this point, because of the isolation gasket melting (no thermal paste, led board not really squeezed down because the reflector is just not touching it when srewed tight ).
Then I changed the led board to a Sinkpad with a XM-L2 3C, Arctic silver 5 in between, pill not completely screwed down (just half a milimeter) because then the reflector does indeed squeeze the led-board tight against the pill. (I changed the melted isolation gasket for a new one).Current went down to 3 amps (perhaps because of the higher Vf of XM-L2, and/or lower working temp?), but the light can easily handle a continuous high now.
Last thing I did is soldering a 330 kOhm resistor over the light-brownish capacitor (as suggested by Relic38 somewhere else) and got rid of the next mode memory, it always starts on high now.
I has become a very nice light and I just gave it to my friend, he has no idea what happened to it, but he is very happy :-)
Bottomline for me is that, although generally it is considered cheap and ready to swap to a better one, I quite like the driver (it is in a variety of lights by the way, as already stated above in this thread), it is simple enough for me (I am no electronics guru), with a very simple move of the +wire in this light it is getting 3 amps to the led (same current with a Trustfire 26650 I just found out), and the next mode memory is easily removed with a resistor on top of the capacitor. Oh, and I could not see the PWM on low,when waving the light before my eyes, so that must be pretty high for a change.