05 na cat question

Here be the issue. I have po420 code good o2s. So i am gonna have to mortgage the house or sell my wife to replace the cat(s). 700ish is what local dealer is sayin. Hard time findin aftermarket. But walker does make exact fit for ej25 impreza. Will this bolt up or did subaru waste buttloads o money creating different flabges for what appears to be an identical cat unit. BTW walker is $349. Thanks in advance.349