Look at my brakes. I did the upgrade you did. There was no difference. So now I went to the Wilwood 6-piston kit and have never been happier. Cross-drilled rotors are for cooling and outgassing. They *could* help to reduce fade, but they will not shorten stopping distances...especially with the tiny stock Z rotors. Take your car to a road course and you'll last 5 minutes before your brakes won't work. A more aggressive brake pad will decrease stopping distance but not the rotors themselves.