OK I won't be a smart**s, but I am serious. Unless you're doing something unusual, the car out of the box is all you need.
If you are doing oval racing or carpet racing or like rock climbing, something like that, then you need 'hop-ups'. If that's the case go to where they run and find out what they are running and where they get it.
Otherwise if you are backyard bashing you could strengthen parts you break a lot with aluminum. But remember that if one part is aluminum something else will be more likely to break.
If you want bling and flash you can find all kinds of snazzy parts out there. You could have a 100% titanium shiny blue B4.
But if you want to race electric off road then stick with what AE gives you. MANY World Championships can't be wrong.