would a stock 03-04 cat work on my 2000 imprezza rs?

i need it to pass aircar and my car has a test pipe...

i bought this car used so i dont have any stock parts...

or if i go do dealer, would this part be exspensive?

Thanx

 

Another option:

http://www.rs25.com/classifieds/show...1&cat=4&page=1

Sorry, don't definitively know about the fitment of the newer models, but am inclined to say yes it will (so that is no help prob.)