Upgrades? This really all depends on what body you use, and with what chassis.
For my car, I upgraded with:
en I put a heavy body on it, the car bottomed out. So, I didn’t change the shock oil, just the springs. In the end, the springs help hold the car up, and it could be better, but that was the only consideration.
Overall handling….my car is difficult to drive and doesn’t handle good at all….in fact, it’s terrible and takes a lot of effort to keep it from flipping or just going fast in a straight line. That being said, it looks pretty good on film cause the heavy body and springy springs help it look like a real 69 charger, which is not a good handling car in stock form…just like TV.
For me, on this car, it was more important to look good on film than to actually be easy to drive or really fast or turn well at speed.
Metal CVD rear drive shafts, this was important for my car due to the heavy body and small chassis…..the stock ones are plastic, which might be fine for some builds, but not for what I was going to do.
Lipo battery, I stayed away from Lipo for a couple years, and I only bought one because I kept melting 2/3A size NiMh batteries, but once I went Lipo….there’s no looking back. If you buy a decent well known brand, and treat the battery with respect….100% satisfaction, awesome power and performance.
In order to get my heavy car up to speed in a short distance, I needed battery power, 7.2 or 7.4 wasn’t going to get it done, so I was using cheapbatterypacks.com and buying custom 9.6v 2/3A battery packs. They had plenty of juice, but my brushless motor was pulling the kind of amps that was borderline of what they could deliver = melted batteries.
Lastly, weight….Lipo batteries are a lot lighter, so I like using them because I can control where I put the weight in my car, so it can help with jumps or power slides.
Traxxas brushless VXL3m motor/esc, I used the stock 1/18th 380 size brushed motor for about 5 battery packs….car was just too heavy. I tried the early Mamba 1/18th brushless system….didn’t have good results with it….too heavy, then Traxxas released the VXL3m and it worked great. If you’re using a 1/10th scale chassis….you could probably use stock type or brushed motors, etc if you want.
Ball differential for the rear axle, The stock plastic tooth differential was not going to last, due to the weight, so I upgraded the to a ball differential, and pretty much have it set “locked.” I just put it in so there is one less part to break.
These mods were due to using a 1/18th scale chassis for a almost 1/10th scale body, and a HEAVY body at that, plus, I knew what kind of punishment, ( burnouts, jumps, jumping, and more jumping ) I was going to put it through.
In other combinations, with other intentions, you might not have to do that.