Nah. I never said change the engine. Where did you read me say to remove the EJ22 engine? I didn’t.
Bolt the EJ25 intake manifold onto the EJ22. Leave the EJ22 the original EJ25 ECU will run it just fine
“Reinstall the original EJ25 ECU and EJ25 intake manifold and EJ25 oxygen sensor.”
Try here for the O2 wiring: https://jdmfsm.info/Auto/Japan/Subaru/
There are more Subaru wiring diagrams posted on other sites too.
No offense, but you stated in the 1st post - that you swapped ECUs, and didn't mention that the EJ251 was no longer avl., so that led the USMB to the info above.
I'm not going to say it stayed extremely clean (we tried) but there wasn't really any dust to worry about. Dirt falling off the bottom of the car, yes.
If not for the cage we would have parted the black Outback out a long time ago. Or so I keep saying.