Just for the craic!
Remove your backbox, Just two bolts just behind your back wheel, soak them with WD40a while before, and let it hang down away from your center section,
Start her up and give her a rev and see if that is the sound you are after!, if so, Get your hands on a back box, I'm sure some one will have one around!
Have a look under your engine, at the front going from left to right, you will see your headers, If they are covered with subaru branded heat sheilding then you more than likely still have your standard "rumbley" headers!
Have fun!
Dan