If you have no mods yet, a lot of people start with air intakes (Gen 3 from Stillen) and an exhaust. The exhaust helps the engine breathe, which is essential when modding a car. Seems lots of poeple here like the HKS, Stillen, or Fast Intentions exhausts.
https://specialtyz.com/shop/fast-int...50z-03-10.html
https://specialtyz.com/shop/370z-g37...ntake-kit.html