I don't know if OP's intent was for racing or just bashing on a rough & loose track, but box stock setup has been great for me so far, and I trash (track bash) my ET410 on a very rough rutted medium-loose track.
The stock suspension setup/shock package is almost perfect. I was expecting the ET410 manual's stock setup to be on the firmer side of things. But, after running the truggy for awhile, it soaks up bumps/jumps, and flies very predictable (with SC tires)...better than I had hoped for.
My only complaint is the rear yellow springs are too stiff to get desired ride height. I can't see anyone using the stock rear springs to get a low ride height, unless, a different shock tower is used, or the coils are cut ?. I currently have to use the 2.61 lb/in, green springs in the rear (and find them just barely soft enough) to get the truggy's rear at "bones level" height that I strive for. This is only possible when rear spring collars are adjusted so that they are only touching the rear springs while the springs are fully extended. I will be getting the softer pink rear springs shortly, and they should be (hopefully) perfect for my situation.