I bought these as an upgrade to my stock rotors for my 2014 Mustang GT. I didn't install them for a few months after ordering. After I installed them I experienced a great deal of modulation while braking. Braking was not smooth at all. Because I waited so long to install and did not have any of the original packaging I did not try to return them. I did order different rotors and braking is back to being very smooth.