If you can deal with the slightly more painful tax. ej257 isnt bad.... more torque and actually, certain variations are even more powerful than the 207....I think the engine conversion should be quite direct since XV's is based on the Impreza platform. So, you probably can go for the older EJ207 engine or the newer FA20DIT engine. Avoid the 2.5 litre EJ257 engine. Larger displacement but produces slightly lower output than the 2 litre EJ207 engine.