Can't check mine now (@work), but I know my K40 performs well - got mine in the group buy. That dark look is bazaar 
.... Don't think I ever seen anything like that. The depth of the reflector explains the tighter beam pattern - a tighter beam pattern doesn't always mean better throw, I've seen several times, as is in this case.
But with the almost similar specs of the two reflectors, their outputs using the same LED source should have been close. I agree that deeper doesn’t always mean better. The dedomed Vostro gives 223 kcd and a very tight hot spot at measurements taken at 11 meters. The dedomed D01 on the other hand gives 233 kcd and a wide hot spot.
My guess (if its not as is from the factory) is that the dark reflector of my K40 is a result of tarnishing. I’m working in a Geothermal Field and metal parts of our equipment and tools here like brass, copper, aluminum and stainless steel tarnish easily. I think its because of the H2S in some parts of the field. My K40 is the most opened flashlight I have because I learned to mod using my K40 and many times during my learning phase I continue modding during breaks at the office. :bigsmile: From now on I think I should limit modding at home.
Pure copper pill for this Courui available: ( by NikolaS )
Thanks tatasal for sharing my offer ………
Guys, take a look at this: !!!
Courui "Even Bigger Head" D01 Projector: 113mm Lens , Luminus SBT-70 @ 13.5Amps *Build Stage* (by LinusHofman)
Perhaps going to be the ultimate `Big Head`….(this thread, and that of NikolaS, now added in OP)
I am sorry if I missed this mentioned,
I want to know if there is enough room to add a “blank” PCB between the batteries and the head (converting from 3P to 3S).
2 of the cells will need to be insulated from the head by the PCB. I am wondering if there is room?
thanks
This has been done before:
I think CK is also working on this
I ‘shamelessly’ copied FmC’s mod last night and got 3010 lux at 11 meters which can be computed to 362,210 cd or 1207 meters throw. 
Also got 3.62 Amps reading at the tail cap with 4.13 volt batteries. 
This is now my strongest thrower so far and I’m really loving this light.
Quick question guys, if I piggyback two R100's on top the existing R200 what should that compute to for current?
-Garry
Assuming fully charged batteries & resistance mods, I’m guessing around ~3.5 Amps. Could be a little more.
Well my Courui mod didn't go so well (: . I had a short at the reflector due to a sharp peak of solder (which I couldn't see) poking through the kapton tape. I smelled a little bit of a burning smell but I didn't see any bad components. I found and fixed the solder peak then tried it again. It worked, but output looked really weak. I do have the "moonlight" mode when off, then outputs look like Low then High instead of High then Low. Highest output looks around +/- 200 lumens or so. Tried different batteries (first started with a single weak cell) but still weak output. I ran out of time to work on it and put it away all disgusted.
So do you think my driver is ok since it's still giving me modes? Could my triple stack of resistors be an issue? (I don't see how it would be any worse than a direct short across the stock one.) Would this be typical behavior of an LED after a short? (Still works but output way low.) This was a dedomed XM-L2 on copper.
And by the way, I had an awful time trying to get the reflector centered! The butterfly insulators don't "snap" to the reflector opening to hold it centered.
-Garry
FmC that seems awful low. I read some other mod posts and came to a conclusion that adding one R100 should have been sufficient. My objective was to have nearly direct-drive performance by way of ultra low sense resistence.
And you responded moments before I posted my new issue.
-Garry
It’s soooo easy to short out the driver with this reflector 
I’d say that you have burnt out one of the Fet’s.
I guess it depends on what type of battery you are using. Honestly, I’m just guessing on the figure here. With high drain cells you may well see over 4 amps. …well, you may have, before it was damaged…
Time to get a BLFDD driver in there!
- edit - I looked back through my own thread, as I was sure I had taken some current readings. With the resistor completely bridged, I saw just over 4.5A using a fully charged 25R.
Hmm, ok. So you think the LED is still fine most likely? I plan (when I get time again) to try and connect an 18650 direct to the emitter wires and see if it has the output level I expect. I kind of already did that during my first investigation but the light was face down and I was only interested to find out if it lit up.
-Garry
I have (3) 4.35v cells for this light, but haven't uses them yet as I wanted to make sure it was working properly first.
-Garry
My guess is that the LED is OK.
I’ve done several Courui’s, & managed to short the reflector in one of them as well…. same symptoms. A few others here have done the same as well.
It seems like those little Fets are not very robust.
Those little FETs aren't easy to buy and replace, are they? I'm guessing not.
-Garry
I would also say it’s a fet gone “wild”. In my experience leds are really hard to kill if you are not planning to kill them.
Try other driver with that led and you will see.