The uppipe catalytic converter is a liability, the best thing to do is to remove it and use the resistor fix for the EGT sensor. That's the first thing that should be done to any 2L WRX, and honestly, I wouldn't drive a car with it in there. Not only does it hinder performance, there are multiple accounts of it failing and destroying the turbo. If I were you I would either gut it, or look for a used 2.5L uppipe to replace it with. It can be the source of many problems and replacing it with another catted uppipe just doesn't make sense.