HI:Want to know,can a 2003 impreza wrx after market 3 inches bore, cat back bolt onto 2003 sti? Thanks

 

As far as I'm aware they 100% interchangable

 

iv just got an 3" cat back after mkt system for my bug sti and it wont fit up to the 3" scoobyclinic down pipe it is to short or the 1 piece down pipe is not long enough the people i bought system said i might need a two piece cat

 

hi, if you want 3" i would pretty much say you need to go full system ie turbo back milltek or something similar.

i had one of these systems http://www.scoobyparts.com/acatalog/..._NEW_AGE_.html
fitted to my sti ppp downpipe for a while before i went 3", sounded good looked great and got good money for it when i sold it on..... hth