In spite of all the negative comments, I have AP Racing's 6/4 piston f/r caliper brake kit and have been VERY pleased with my street and road course braking ability. NO BRAKE FADE! It's like night and day from stock brakes, and upgraded rotors with upgraded pads and steel brake lines. Oh and NO nose dive. You can also ask Ash. He drove my Z and he liked my brakes. I also went with a big brake kit with a 6 piston front caliper for my A6 since it too is a heavy car. IMO, the more braking ability, the better. For some odd reason, we all want the ability to go faster, but most of us don't want to invest in the ability to stop better. The Rotora 6 caliper gets my vote. Z1 has them. I'd go for the 4 piston caliper rear set up too.