I have a project impreza OBS that I've built for off roading. The ej22 on this thing kicks rump roast and even though it's the phase 2 its still reliable as hell and has never left to die in the mountains. That being said, I'm getting real close to committing to an ej25 swap because i'd like to be able to use freeways again with the big rump roast tires and bumpers i have on this thing. How realistic/easy is it to bolt on ej22 heads to the block of an ej25 and how much horsepower can I gain with this swap? I'm thinking of going with a 2.5 from a 98 forester because they share the same chassis and have the same engine mounts (almost positive). Can I still use the same cams, valves, injectors, timing belt, water pump... blah blah blah from the ej22? Will the headgaskets from the 2.5 fit the heads of the 2.2? Lastly will my ej22 intake manifold bolt right on the the block of an ej25? Will my ecu freak out or would it just be chill with the swap? I'd appreciate any and all contributions. Thanks guys.