Check out this article from Mustang Monthly, link was on American Muscle's website.
Not sure if it is out of date or not... September 2012... Something may have better results by now. 2011-2013 Mustang GT Cold Air Induction Buyer's Guide - Chilled Coyote - Mustang Monthly Magazine
2011 GT Premium, 400A, MT, Black with Stone interior
My Mods So Far (in order): VA Legal Tint, Polk DB571 Speakers - Front & Rear, Third brake light pulser, MMD Classic Louvers, GT500 AB, Bondra Performance EZ-Clutch Pedal Extension, resonators cut out - do this!, Steeda shorty black antenna.