Pretty simple really....google the part numbers and see what they suit.

Pretty easy to work out with 5 mins of your time.

STI one won't work on your car as the actual air flow Vs afm response would be way off for your WRX ECU.

also your WRX one may be a 5 pin AFM V 4 pin for the STI both use the same plug with more or less teminals vacant.

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