With these older drivers it is possible the current might be increased some just by changing the sense resistor. Its usually a easy mod if you have a soldering iron.
If you can get the driver out with out to much trouble and take a good close up pic, we might be able to help with that. Just depends on what Olight used for regulation.
If you want throw go with a sst-20.
two wire emitter swaps take old to a new level and the ability to look at a new tint.
Is the reflector smooth or orange peel ?
If you can't get a decent beam .Dc-fix will soften the blow .
If it's an olight I'd consider changing the glass to non coated clear glass .none of it overly complicated and like you said ... could it get any worse ?
The driver is on the bench so I’ll try to get a pic tomorrow.
Hmmm. sst-20 you say. My FW3A is coming in sst-20. The reflector is OP. Something else to think about. Was planning to replace or scrub the glass. I have put sapphire glass before in when I can.
Ok. So I have a couple really nice pictures of the M20 driver I took with my S 9 phone that I can't figure out how to upload to this thread. I'll keep working on it. In the meantime I think I might get several LEDs on boards and try them out.
Here’s a guide that might help.
Ok. Here’s one photo of the driver.
On the very bottom where the black wire is, there are two resistors connected to that solder blob or it looks like there in parallel with each other.
The very bottom one reads R20 it looks like. The top one I can’t really tell. Could you possible take a clear pic of that area or check with a DMM and see if they are in parallel and also read the value of the both resistors. Looks like those two are sense resistors and lowering the value can up the output current but I need to see what they are and if they are in parallel.
Both are R20. I’ll put a meter on it tomorrow if I get a chance.
Don’t think my meter is sensitive enough to measure .20ohms or maybe it’s just me not being able to read it right.
Just need to know if those two resistors are in parallel which I suspect they are. If they are in parallel then the total sense resistor is .100 ohms. Adding one more R20 (.200 ohm) in parallel gives you .066 ohms total. That should bring the current up a little over 1 amp. Adding a .100 ohm should give you .050 ohm total resistance for around 1.5 amps. This is of coarse if all the other comonents can handle it. That’s probably about as far as I would push it not knowing what all the other components ratings are. To get any real current to the led you really need to swap drivers. Running at twice the current as original will reduce your run times about in half also.
Adding another resistor, simply stick another resistor right on top of either one of the existing resistors and solder the ends to the existing resisor, we call it piggyback 
.
If you want to experiment in resistor combos you can use a online parallel resistor calculator.
The sense resistor looks like its maybe a 805 size. You have to measure it to be sure.
To check if the resistors are in parallel, set the meter to continuty or resistance and place one probe on the right side of the first resistor and the other probe on the right side of the second resistor. They’re should be no resistance between the top and bottom resistor ends measure on the same side. Top and bottom right side and top and bottom left side. If you get no resistance they’re in parallel.
There’s no resistance at the resistor ends so I’m sure they’re in parallel. It wouldn’t be too hard to do that mod. But if I were to consider replacing the driver would you have a suggestion as to which one. The M20 has a forward (tactical) clicky. I’m not sure what type of driver would work in that case.
BTW, I really appreciate the answers to these nubie questions. 
I think this one will fit with a little filing of the sides its for a one cell only though. You didn’t say if you plan to use 2 123a’s or a 18650. You’ll definetly need a copper mcpcb with this one and a Led that can handle it.
Not sure if it works with a forward clicky but Richard at Mtn should be able to help with that.
The bad news is it’s not in stock, so there’s another question for Richard.
Oh and by the way, you said this was going to be a throw in the truck beater. You’ll probably be better off with the safer primary 123a’s stored in a hot truck.
Mod the driver sense resistor and swap the Led and mcpcb and call it good for a safe truck beater.
Thanks for the info. I do use primaries for stuff I seldom use or might forget I even have. Probably will just do a LED swap or 2 and see what I can come up with. I do like the option of having different cells to choose from. Might have to find a different truck beater light though if this project turns out well enough.
Got to be something else around here I can mod next.
Just a follow up. I finished the LED swap using an XM-L2 U3 3D LED on Noctigon 16mm MCPCB from Mountain Electronics. I also replaced the glass lens with a non-AR mineral glass.
Overall results are very nice. I really like the tint and it is definitely brighter than it was although I haven’t done a comparison with any of my other lights. I did lose a brightness level though. It use to be low, medium, high and strobe. Now it’s just medium, high, strobe. Not a big deal for me since I didn’t care for the twisty UI for changing brightness. Maybe someday I’ll mess with it some more. Thanks for the help to my intro to modding.