My car ('05 STi PPP) was fitted with a Cobra Sport cat back system when I bought it. Sounded nice, but droned like a mofo on the motorway.
Then tried a very lightweight STi exhaust which eliminated the drone... but was too quiet!
Finally settled on a Nur Spec R. I'm still running the front cat and thats spot on for me. Flat four burble at all times, nice growl when you put your foot fown and no drone on the motorway, hurrah!
My advice would be to have a listen at a few meets though: can't beat hearing an exhaust for real to decide whether you like it or not.
