Yes, heard of them and actually sell their products. I haven't really heard them in detail as far as the exhausts.
Not to sound like a fanboi but I love Magnaflows and plan on getting one for my STi sometime soon.
We have a great deal going on for them on the Sedans as well:
MagnaFlow Catback System 2011+ Subaru WRX / STI 2.5L Sedan  - $620.00 : Kronos Performance, Fueling the Car Lover Within