how much power do you want?
- Finish exhaust (dump pipe and front pipe) + remove cat or buy highflow cat
- FMIC kit
- safc or similar (depends how much u want to spend, cheap go piggyback aka safc, lots go full aftermarket $$$ or ROM-tune of stock ecu)
- fuel pump (really only needed if yours is old and not working the best)
- Rb25 turbo
then retune, the rb25 turbo will give you relatively good power without too much lag.
to reduce cost fit the items yourself, to help keep cost down you can buy china brand fmic, exhaust parts the difference between china and brand name is relatively small in those parts
enjoy and drive safe