there is an outback here with similar ej engine...
is the impreza turbo?
I run old subes for the eco stuff. singular point injection maxxed at 38mpg (limts of gadgetry).
add three injectors, twice as many valves, a smaller oil pump, two more main bearings...on an engine that dfoes not keep solid state momentum.....yikes.
the impreza at occasional 27 may be the best it has to squeeze out already. I would not complain. if you seek longevity and a bit cleaner/cooler/less pollutant, the sube and EGR hate each other, you may be able to block it off.
2 valve heads and carb would bring into what you want...
just not likely with todays setups.
