Is there a need to run the 2 speed transmission with that much power on tap?
Converting to the Gorilla Maxx single speed transmission will save you the weight of the gears, transmission case and shifting servo. You also gain vital power through less rotating mass. Total weight saved approx 100g.
Once the shifting servo is gone move all your electronics to the front of the truck, which will shift 200+ grams from the back end of the truck to the front.
You dont really need the gear cover. Most the Emaxx's at our track dont run them and I dont know of one of them that has ever had a problem with getting rocks in the gears. Plus it will give the motor plate a little more air flow.
Looking at the amount of spacers on the rear shocks suggests a decent set of alloy adjustable shocks all around might improve both weight and handling as well.