Ok, so as a few comments, and suggestions have wondered, i will make a post about modification.
so engines function is obviously to power the car, and essentially just move the wheels. (with a few side functions like heat, power ect.)
to keep it simple, think..how will this improve my engine. will it help apply more pressure to the piston for a greater explosion? will it help everything run smoother, or with less resistance? will it make stuff last longer?
turbo's like i mentioned add more pressure to pistons aiding a greater explosion of fuel. you can purchase a turbo that is designed for an engine like yours, and fit it with no issues. this is a popular addition.
other things to consider is an exhaust to give less resistance to the engine, a better filter, or intake to give cleaner, or more air to the engine (one of the key components to burn fuel).
how about what gives the engine fuel? you could add a better fuel injector, or perhaps a new engine computer that is programmed for power instead of economy.
all in all filters, and intakes are a very good place to start. after that i would go for injectors, and components of such.
modern engines are controlled almost completely by an ECU, or the engines computer/brain.
if you want to maximize performance then this is not a place to skip. it controls when fuel is given, and how much is.
i am not very knowledgeable in the modification area, so i apologize if not all of this is completely accurate, or good advice.
how would everyone like to hear about suspension next? transmissions? any questions?