Wow, the amount of misinformation in this tread is amazing!
WRXs need R180s (or R160s with custom hybrid axles: wrx inside and STi outer CV and axle stud) to run the rear STi 5x114.3 knuckles and hubs.
Please search for 6Gun or posts by javid in the suspension forums. I have posted tons of info, parts, reasons, ect.
I need to write a FAQ....