V8Killer is the man on these swaps. I personally would not recommend a GTiR swap as they are a pain in the ass for parts availability. They do not share all the parts as a US SR20DE. I personally would just slap on a turbo (which is what I am doing) onto the existing motor if it runs good. A USDM sr20 can support over 400hp (if done properly) without opening up the motor.

GTiR motor : $2,000 - $3000
Install: $800 - $1500
JWT ECU: $600 - $700
MISC: $500 - $1000
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Expensive


If you slap on a turbo:
Turbo (GTiR T- 28 ): $600
Mannifold : $250
Install: $500
JWT ECU: $600 - $700
Injectors: $150
MISC: $500 - $1000
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Affordable