Here are some suggestions:
-Lose the Tamiya connectors for the ESC/motor and solder on some 3.5mm bullet connectors. They have a lot less resistance, are a lot less bulky, are easy to solder, and the biggest reason why I stopped doing that: What do you do if you find your motor rotation is reversed?

With bullets, you just disconnect and reconnect them the opposite way to reverse the polarity. With Tamiya connectors, you have to completely disassemble them, reverse the wiring inside, and reassemble them.
-For ESC-to-battery connections, consider EC3 connectors. They're much easier to solder than Deans, almost no chance of shorting the battery leads while soldering, don't require 3 hands to solder, don't need heatshrink, and it's impossible to reverse-connect them--with Deans, it's possible to insert the connectors together enough to short the battery.
Nice, clean car so far!