I saw a Black 05 GT in the Parking Spot lot today that had the exact same thing done. GT badges removed and the old pony badges added. It looked sharp.
2005 Mustang GT, Black w/ Dark Charcoal interior
IUP, Active-Anti Theft Alarm
Bright Aluminum Wheels w/Locks
Perma Plate, Window Tinting 35/20/5
Molded Splash Guards, Sequential Tail Lights
SIRIUS Satellite Radio, Front License Plate Delete