Depends on what you are looking for and if you are auto or man.
Bst bang for the $$ is turbo. But that is probably too much for you. There is Intake
, exhaust, header, coms are coming soon, nitrous, clutch, flywheel, etc etc. The list goes on. For more info, search through the board. you will find sooooo much info. Good luck and welcome to the boards.