As for the exhaust, just look at it. Ford did a beautiful job on it and if you start cutting it up you'll have Frankenstein, Hero-to-Zero and a mess.
Just get those FR Axil Back Sports, they bolt right on and the 4" tips fill the rear diffuser openings better then the stock GT tips at 3". The service Dept. won't even notice them until they hear them. Your Mom would approve and the condescending effete Euro snobs will believe your car is worth far more then your station in life should allow, you pretentious domestic up-start.
I did notice one thing about my Race Red (almost demonic red) car. People for the most part notice it and have an inherit sense of fear of hitting it with their door. I also hope that mal-adjusted; anti-social; zero-liability voter; Skate Punks with entitlement delusions and a KEY (that doesn't open anything but does sate their rage at people with nice paint jobs). I feel they will be intimidated by the color and even though not religious in nature, will wish to CYA should they go where they belong in the after-life. Everyone loves a blue car but it gets dinged.