I don't know if there are still people out here driving the D413, but I'd like to post about a couple of things I made for the car:
A short-shock mod, using Associated big bores. It features slightly less droop, and combined with the shorter length I made this in mind with people who demand more sharpness from the car and for better high-bite performance. I have yet to test them on astro, but on clay the steering already feels much sharper and and it pitches less when cornering.
Sidepods, so it can actually keep dirt out
A new battery plate was also added to keep battery changes quick and in fact make battery position changes quicker with the screw+nut that you can put in the slots of the plate.