Found this article showing the Ford advertises dual piston rear calipers on the Brembo package GT's. These are the same brakes on the Boss with the exception of upgraded pads. I don't see this as a huge deal but what do you think?
http://blogs.insideline.com/roadtests/2011/01/2011-ford-mustang-gt-50-has-brembos-single-piston-sliding-rear-calipers.html
http://blogs.insideline.com/roadtests/2011/01/2011-ford-mustang-gt-50-has-brembos-single-piston-sliding-rear-calipers.html