There isn't much in the way of performance upgrades, nor would I recommend any performance upgrades if they did exist.
Wheels can look nice but will in almost all cases make your performance and/or comfort worse.
Brakes are a pointless upgrade because the factory brakes are already way more powerful than the car needs.
Airflow and exhaust upgrades are pointless because Kia already has the optimal setup there, and the electronics would override any potential performance gains anyways.
So that leaves us with upgrades to improve the looks or functionality. I don't know or care much about aesthetic upgrades, but some people have found light upgrades and stuff that they liked. Personally, I'm more interested in upgrades to improve function. Particularly, racks and rack accessories, cargo area accessories, etc. Some people have found cool ways to organize their cargo, you can find a few ideas in this forum.