Today I fixed a BLF-X5/X6 driver from dropping out of turbo.
In another thread I asked how to fix the BLF-X5/X6 driver from dropping out of turbo in a hight drain triple and I was lucky to get an answer from DEL :-) , it may have been mentioned elswhere on BLF but I had not read it before :

djozz,
Inserting a 2.2 ohm - 10 ohm resistor in between cell+ and the C1/D1 junction will fix the problem. (Stacking C1 is a brute-force method that fixes the symptom, rather than the problem. Tantalum is not great for this, too high ESR.)
You still want to feed the emitter directly from the cell+. IIRC the layout of the X6 driver makes this tricky, but I am sure you will find a way.
(On some drivers TomE’s ‘tombstone’ technique works well. Basically you build a little pyramid with Rnew+D1+C1 placed vertically, their junction up in the air.)
I have a red S2+ shorty that I converted to 18500 cells and has a lighted tailcap (mod here), it worked fine on an Efest purple high drain 18500 IMR cell, but it had the turbo-drop-to-moon problem on the Sanyo UR18500F and NCR18500A cells that are not so high drain.
So today I tried the adding of a resistor between C1/D1 and led+, 'tomb stone style' . The pyramid had to be really shallow because the pill cavity was minimal due to the 18500 conversion, so the solder blob on top was filed down to a minimum. Also, to prevent the touching of the pyramid to the shelf under the ledboard I sticked a disc of Kapton tape inside the pill.
First I soldered C1 vertical on its ground pad, then I unsoldered D1 from its led+ pad and soldered it leaning against C1. Then the 10 Ohm resistor was soldered between led+ (the old and now vacant D1 pad) and the top of the pyramid. The top was then filed as low as possible without damaging the components.
And it worked alright :party: , the drop to moon problem is gone now. When entering turbo, the subtle ramping-up that precedes every mode change in Bistro is not as smooth as on the lower levels, but it stays in turbo alright on all cells now.
Thanks DEL, I can solder alright, but electronics mostly is magic to me.