Once the "gloves are off", you're probably going to find out somewhat quickly (as many others have) that the stock chassis & shock towers aren't worth much of anything. Traxxas REALLY cheaped-out in going with 6061 aluminum. Also, the motor mount & spool holders (since they are separate pieces) are also poorly designed. For the chassis, there are a few 7075 options available...I won't direct you to any specific one, as I don't want to give any appearance that I'm being 'preferential', but an internet search should easily show you what choices are available. Regarding the motor mount & spool holder, check out M2C racing, as they have some outstanding choices (all 7075) that combine them into a single entity, providing extra strength & rigidity. Finally, to solve the bending shock tower problem (that will, sooner or later, happen with the Traxxas 6061 towers), there are 7075 options, as well as carbon fiber (such as BasherQueen) options.
Another "defect" in Traxxas' design was the use of dogbones in the rear...WHY Traxxas went this horrible route, many continue to wonder. Traxxas (eventually) came up with their own solution, releasing rear-length versions of the front CVDs, which does help...but, in all honesty, your best bet is to buy a second set of the front CVDs, and install them in the rear. Being slightly longer, they are less likely to "fall out" of the outdrive cups if/when the suspension is fully extended. Speaking of fully-extended suspension, it's advisable to add droop screws. The mounting holes for such is already built into the lower suspension arms...you just need to buy some. Again, M2C has something to take care of this...but, you can also use the TKR1238 droop screws from Tekno.
There are a LOT of upgrade options available, from Traxxas, as well as others. There's a video on YouTube from Ninth Island RC...I admit the filming of the video probably isn't the most polished, but he does go over some of the best upgrade options available (and provides part numbers)...plus, he has the coolest holographic "oil slick" skin applied to the top side of the chassis. Check it out here:
Introducing the Sledge-O-Matic