If I had to guess it's probably the lower rear valence that prevents the hitch from simply "bolting" up. You will probably have to cut into it for the receiver to clear.
Also, aftermarket exhaust could pose a clearance problem too.
Try e-trailer.com. They might have something that would work. Or even Uhaul.
12 Black GT500 SVT PP l VMP TVS l JLT123 l O/R X l 28x11.50Rx15 M/T Street R's l BMR Suspension l Recaros
03 Sonic Blue 3.8 / 17 Magnetic Fusion Sport 2.7 EB