If I was planning to buy a D4Sv2 and swap out the leds for FFL 351a, which led should I order initially? Are the 519a similar enough in current draw? I’d be getting a Lume driver btw
order the flashlight directly from @JLHAWAII808. Maybe he has the combination you want
I was thinking about it but the markups are a bit crazy TBH.
Hank:
Base - $47.89
SS Bezel - $2.99
Emitter - $0-10
Magnet - $2.99
Lume Driver - $14
Total: $77.87 if you get 519a emitters
JLHawaii:
Base - $79.88
SS Bezel - $2
Emitter - $8-$48
Magnet - $0
Lume Driver - $22
Total: $118.88 for the exact same config. That’s a 52% markup.
For that kind of markup I’d be better off learning to solder
You don’t know how to solder?
Always seemed like it would be better to let someone who already knew how do it. Barrier of entry–don’t have the iron, don’t have any experience, and I didn’t want to practice on anything I cared about.
I have a few lights from Jackson and the quality of his work and support he offers after sale is worth the markup to me.
Edit: When I add Hank’s express delivery fee ($25), the difference is smaller too, since Jackson ships from Hawaii and it just takes a few days to mainland US.
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If you’d be swapping the emitters you’d also need a hotplate.
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I will say I’ve seen multiple examples of Jackson’s work and it’s excellent!
I’ll even say with confidence, it’s better than if it came directly from Hank.
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Would Firefly X4Q with FFL351a at $50 be a candidate? Lume X1 driver. Quad FFL351a of your choice. The 4000k is pretty rosy and the 3700k looks to be more neutral. https://www.firefly-outdoor.com/products/x4q-comet?variant=46244601397462
I have no experience with this X4Q host and its LEDs (ie pls check review) but the other Firefly lights I do have are my most favorite among all the lights I have bought, including my D4V2’s and D4K. Absolute premium quality. Beautiful color rendition, either rosy or more neutral depending on choice.
To swap the LEDs you have to remove the MCPCB. That means desoldering all wires first, including the wires for the aux LEDs. They are tiny and it requires good soldering experience. Then you need a hotplate and all the accessories. So only for the tools you can add $100.
I agree if you want learning to solder but i suggest to start with an S2+ before start with a D4S.
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When i mod my D4S i found an horrible hole that probably came in the machining production and Hank cover with a piece of material and glue… I hope it only happened to me…
Unfortunately my first experience with Firefly light was not a positive one.
They sold out-of-stock without disclosure and then ignored inquiries on when the item might ship. Once the thing finally arrived a month and a half later, there was flux spattered on the LEDs and the I didn’t like the button feel.
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Sure it is cheaper to buy the light now, but what about after several lights and maybe some other projects with light soldering? I think it would pay off in the long run
A soldering iron and a hot plate are always useful if you plan to modify more flashlights in the future. As others mentioned already, just start with simple emitter swaps where you need to solder only two cables, then move on to reflowing single leds on the hotplate. The D4S is a relatively small flashlight where the solder joints need to be small. You have to solder four tiny cable for the aux leds and two for the main leds. With a little practice it can be done.
Let me remind you that once you start to modify flashlights the rabbit hole gets a lot deeper … 
The Lume X1 is a boost driver, it can’t deliver more than 2A per led so your FFL 351A leds will be totally fine.
This is not entirely correct, as it is 3A-per LED on a D4Sv2 using the LumeX1 (which is set up for 12v 3A). The '2A per-LED" is only for the old 24W boost driver, which is only used new on the 18650 lights as far as I’m aware (D4v2, D1v2, DT8, etc)
The FFL351A will still be fine with 3A, though.
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