I had a Maddad Whisper before and now I have an STi catback.
The Maddad is one of the best sounding exhausts ever, and it's not loud at all. It's barely noticeable around town until you get on it. But when you get on it, it opens up and has a very, very nice tone.
The STi catback is barely audible ever. You don't hear any exhaust note, just a "whomp whomp" from the boxer rumble. I would say this is too quiet.
I regret getting replacing my Whisper with the STi catback. Also, the Whisper is very well-made. It could hang up in a museum.