i don't know what your goals are.
but in my OPINION the best way to start modding a car is with the brakes first, you have to stop first before you go fast. then suspension mods to make it handle, more fun per $$$ spent. you might enjoy driving the car this way and stop modding. if not then start modding the motor to go faster.
My opinion is the same. Says the guy remaining stock. I did suspension & brake upgrades on other cars, but since the '09 is "just a driver" to me, no mods.