So I want to swap a motor from a 2001 outback
2.5 single head cam
From what car to what car? If this is the same year car and same engine you should not have a problem.
I want to swap from a 2001 outback into a Impreza 2006
Those are different versions of the EJ engine. The older engine is probably an EJ251 and the 2006 probably has an EJ253. I suppose this is possible but the problems you will run into will make this not worth it. If you are subject to smog checks your car would likely fail with the older engine.