suminahh!

Yeah I'll bring my rs and might see if my mate might my old imperza down to

I found out want it is and turn out to my some of my piping for my front mount was popping off so I've had to change it cause then guy who done it easy way hope it worked

Clean or replace the Maf meter, also could be a coil braking down if you have cop

You mean as then coils that are on the end of the spark-plugs ? And do know how much it would be for new ones ?

Sorry, but this really needs to be mentioned. Putting a 2.5L motor in with an untouched 2.0L ecu is a receipe for disaster. Yes, they may be able to self-learn, but this is a very fine adjustment, used to help correct light knocking etc. IT WILL NOT suddenly adjust your injectors to feed an additional 25% more fuel. If you think you can do this, go for it. But you WILL hand grenade the engine.
 
Sorry for the rant, but there is some really interesting comments here.

Yeah you may have a point there mate but I have done the swap myself and it's run fine and yeah it still using 25injectors just had to get wire the injectors plugs on so it worked but yeah it dose run a bit Len and that but there at part you have to change from the ej18 for it to work but run fine

didn't know about the 25.. but i know you can drop the bottom end of a ej22 in to a 1.8 prez and just change the injectors.. it runs fine.. 
 

about the only NA change worth doing on one of those old crappy FWD ones..

Yeah I had the ej22 in my car why I was working out how put the ej25 in but it's just same way in a how you put the ej22 in to run it by change the crank sprocket with putting the one on so it fire right and and some other things but you don't need to change the injectors and after put the ej25s In my gc8 wagon that it's lot more better to drive and is moves , would have be my best n/a subaru I had why I was on my p's but I'm looking at selling to get foz gt