I am trying to wire in a Apexi Super Air Flow Controller II in my '02 WRX, but i am having trouble finding the right wiring diagram. Does any one know or know where i can find the exact engine model of my ej20.. the 3rd digit?

Engine is an EJ20. Often gets referred to as an EJ20t though in reference to the turbo.

Check the vehicle handbook for further details.

Actually its a EJ205 motor not a EJ20t... The USDM 06 WRX engine code is a EJ255 with the 2.5 motor in it... The USDM Sti motor is a EJ257 just some FYI

Actually, the engine codes aren't even that simple when you get into the actual shop manuals, but you're right in those last digits.

Ironically, I only managed to get my hands on that info in the last week myself.

There's a label on the front of your timing cover that has a barcode and the full engine model and serial number on it. It looks like this:

http://i23.photobucket.com/albums/b378/draglarry/sti_stuff/STImotor008.jpg