I finally got around to doing some more mods to my TWDLE and can report back. I already have the Stern topper, aftermarket zombie shooter rod and Stern art blades.
Here is what I settled on at this time.
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Power distribution block (for power sources for mods) (Pinball life)
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--Interactive--
Gnassel BG light version 1 option A (on Pinside)
Stern shaker motor (SP14) (Stern)
Hitchhiker prison sign (Mezel mods)
Animated backbox LED lighting (I didn't know about this version until doing some internet searching, nothing about it in the TWD threads that I've seen)- http://flipperfidelity.com/lighting/animated-led-backbox-light-replacement-panels/stern-the-walking-dead-le-enhanced-animated-led-backbox-light-replacement-two-versions-dimmable.html
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--Cosmetic--
TWD ramp lights - blue (Mezel mods)
Woodbury sign (not lit) (Pinball life)
Crossbow (Mezel mods)
LED RGB Speaker lights and TWD grills (speakerlightkits.com)
Red LED flipper britebuttons (Pinball life)
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I will have to wait on prison tower (oos), PDI glass (later) and color LED dmd (not released) in the future.
I am still waiting on the BG light and speaker lights/grills. I will post up when I get that done. I also need to install the interactive backbox lighting which just arrived, and hope to do it shortly.
So far I'm really happy overall with the mods. Relatively subtle changes and improved looks.
Shaker is awesome and the machine was already setup to add it. I really like the look of the blue ramp lights (contrasts the red lighting on the pin) and it makes the pin look even better. The hitchhiker sign looks great and works with the prison nicely and the piggybacked interactive lighting. The woodbury sign is a nice inexpensive touch and there's no need for it to be lit or interactive considering there is the woodbury playfield insert. Nice touch on the LED flipper buttons. Notably brighter and evenly lit compared to the ones on my POTC from somewhere else. The crossbow has been finicky, but that was to be expected from the feedback. I had to file off some of the material on the mount so pinballs coming in could clear it. It also wants to sit a little tilted (unflat) left to right making it tricky to clear the apron and afix using the adhesive. With some additional fiddling and more adhesive I should be able to get it to work better. I did have to reshim the apron as discussed in the installation instructions.
My friend did the installs. It took some time, but wasn't overly difficult. He is no pinball service expert so I can recommend these mods to those with basic skills.
In conclusion, listed are some mod options to consider, and not too much work.