I'm a big Thundershot chassis fan and have built a few of these cars recently, with my latest one being quite modernized in parts and design. I also raced the car at my local off road track, and quickly found areas of the car that needed improving.
To lessen the chance of having to replace parts on your car, I suggest the following:
Buy or make a brace plate to go over the A5 part. There used to be a guy on ebay that sold them, but you can make your own from some sheet metal.
See those blue solid upper control arms? Get them off there! They are quite hard to come by now, but try to find yourself a vintage Terra Scorcher upper arm kit. The gearbox plastic is very brittle, and the force of the upper arms moving front to back from good jumps and impacts will fracture the ears that the hinge pins go through. Switching to the ball end upper arm kits will eliminate that stress and save your gearboxes. Hell, you can probably MAKE your own uppers if you are handy.
Those are really the two main breakage spots on that chassis. The rest that I would suggest is all performance related. Not sure how far you want to take your car.
Here's my heavily modded "Terror Scorcher". It weighs 1550grams with a 3000 NiMi pack and was easily keeping up with B44s and Cat SXs at my local track. Well, in between breaking, that is
(BTW I have since changed out the rear upper arms, and also switched to a carbon fiber front shock mount)
