Just installed FRPP Duals
Cost was a little over $600 from CJPonyParts - the kit came with the Bullitt mufflers. I had access to a lift, so it was fairly easy to install. Ford calls for removing the passenger side converter to install the x-pipe, but we were able to install w/o removing the converter by cutting the passenger side pipe about 1/2 inch shorter than the driver side.
Getting the Rear Fascia Trim bolts installed was a real pain, due to very little clearance behind the bumper cover to get the nuts on the bolts.
Took about 3 hours to install. The only issue was the driver side rear muffler hanger rubbing against the bumper mount - I will trim off a quarter inch or so from the hanger with a Dremel for clearance.
The big chrome muffler tips look great, and it sounds much better than the factory single exhaust, especially at WOT; the car seems to pull stronger above 3000 RPM, will do a few runs with the G-tech in a couple of days to see if there is any real improvement.
2012 GT Premium, black, 6 speed, loaded, scary fast (or so I'm told by passengers Mods:
Clutch pedal extender, WeatherTech floor liners, more on order....the journey has just started