Resurrecting this from the dead...
I just installed a new/used Cobb 3" SS Catback onto my wagon, and mated it up to a Perrin Catless downpipe via a donut gasket adapter.
Thus far after driving it I'm pretty happy with the sound! It's fairly mellow, and doesn't seem to drone on the highway. I usually drive between 60-70 on the interstate (2500-3000rpms), and can barely hear the exhaust, so I'm rather happy about that thus far as I had heard of droning problems with wagons.
Romping on it, it sounds pretty sweet from inside the car - but it's quiet enough to where I can hear turbo spool sounds.
Fit and finish are excellent, and everything mated up without a hitch.
Thus far after about an hour's worth of driving I'd give it a 5/5. It looks subtle, and everything is high quality.