Here's the stock v6 exhaust vs the GT stock exhaust:
The stock piping size is 2.25" for both cars...that's what is nice about the GT takeoffs, you keep that stock 2.25" size and won't lose backpressure as you do with most aftermarket systems that are 2.5".
If you want to use a GT catback/exhaust you need to cut out the y-pipe and either buy a dual exhaust adapter or have a shop fab up a couple pipe sections from the catback to your catted sections or midpipe if you have one.
It's not difficult to do and isn't that expensive either.
12 Black GT500 SVT PP l 2.6 Pulley/Idler l Airaid l o/r X l 305 NT555R's l Recaros l
04 Azure Blue Mach 1 / 03 Sonic Blue 3.8 / 14 Sterling Grey F150 FX4 402A 5.0 / 11 GT500 R.I.P.