I'm thinking, minimum to start tracking:
- good set of summer tires
- Better brake fluid (RBF660)
- RS3 brake ducts (they are very cheap and supposedly work well)
-Ferodo brake pads (will hold up way better than stock pads with the heat)
You can essentially use the car stock, but if you are a quick learner, you will out grow it very quickly. With the above changes you can track it and really enjoy it, even if you have good skills, the car will perform impressively.
Anything above and beyond that stuff is to get the edge, or to take care of shortcomings that annoy you.
Another change to consider is to get an OBDeleven (big changes for very little money), and do the tweaks that help track performance. The tweaks I personally made are:
- Reduce XDS Setting from STANDARD to WEAK (will allow a little more wheel spin exiting sharp turns quickly, brakes interfere less, you can modulate yourself with throttle)
- Change Brake Stabilization from ACTIVATED to NOT ACTIVATED (will let you trail brake, shuts electronics that keep the car straight under hard braking)
- Change Brake Assistance from NORMAL to NOT ACTIVATED (gives more linear braking under hard braking. If it's on, the car will add additional braking under hard braking. Harder to do threshold braking with it on)
NOTE: If the above changes aren't made, you will most likely wear the brake pads much faster if the electronics kick in to save you / "help" you. Of course, keep in mind, if you make these changes the electronics won't kick in as much, so you may be more susceptible to an accident if you are not experienced in track driving. So do them at your own risk, and understand that it's better to wear the brakes out, rather than crash!
The next change, that most people appreciate after the first group of basics are done and they become a better driver, is a thicker rear sway bar. If you track a lot, especially in the heat, a front mounted intercooler is a nice upgrade as well.
Once you go down the rabbit hole of modifications it is VERY difficult to stop. It's human nature to always want more and better. Each person has a different level that they need the car to perform to be satisfied.
Do some research and figure out how far you want to go, it's more of a personal decision. There is no bad choice since these cars are capable machines right out of the box!