R34gtm8

Best mods for a rb25de Hey guys, i just bought a r34 gt and i need more power, i want to make around the 170-180kw mark. i don't know what to do first. i can't turbo the car but still want to make some decent power. what should i do. let me know the car has already got a shitty cat back exhaust on it. any other suggestions would be greatly appreciated.