Brembo Z04 Pads
First off my setup is a 2008 ZX10R with BSTS running Supercorsas SC2s, front brakes are spiegler ss brake lines Brembo 19x20 Billet Radial Master Cylinder, Brembo HP GP4-RX Calipers, Brembo Z04 Pads, Brembo T-Drive Rotors 310MM. The wheels, tires, rotors and pads were all done at the same time.
First off they are stupid expensive, $137CAD per caliper(would probably be something like 100 USD). I can easily say they are without a doubt the best pads I've used by a country mile. I did some fast street riding which is obivously nothing compared to road racing in terms of braking, but gives a great window of what is to come.
The most important thing is they are perfectly linear. The initial bite is always smooth and manageable even as heat is developed. There is more modulation than the stock pads that come with the GP4RX calipers and or any other pad I've ever used. I use Galfer 1054 semi metallic pads in my Race motard which work fantastic on that specific bike which I can't say is comparable as it weighs 173LBs full of fuel. Being fresh pads and rotors, the rotors still show factory cross hatching which is pretty good in my book. The rotors are still perfectly flat, no rise or edge.
The other determining factor I unfortunately can't answer yet is pad wear. I will try and update this later, if they last a reasonable amount of time and continue to barely wear the rotors, the price is somewhat justifiable in my books.