The major difference between these kits is the rotor design.

Arizona Z car has a custom hat and uses a Wilwood GT rotor.
http://www.wilwood.com/Products/002-...2-GT/index.asp
This rotor does not have a zinc/silver coating so it will rust. However, the rotor is thickest at 1.38".

Brakezone/Evolution kit looks like it uses off the shelf Wilwood hats and rotors.
http://www.wilwood.com/Products/002-...-SRP/index.asp
This rotor does have a zinc/sliver coating so it will not rust where the pad touches the rotor. And I believe it uses a 12-bolt instead of an 8-bolt system connecting the rotor to to hat.

RMS horsepower. I believe uses a custom rotor/hat. The 13.6" rotor I think is priced appropriately between many of the 13" and 14" kits. However, it is hard to say what the internal design of the rotor (directional or straight vane). Seems that this kit fits under 17" wheels even though the rotor is so big.

The rear kit from Evolution seems to use a bigger caliper than the others.

I found one more today. http://fastbrakes.com/shop/ G35 brake kit coming soon, 8/25.

I believe all these kits are "valued" brake systems. It really depends how big of a rotor you want to go with. I just happened to get a 13" kit since I want to use my stock 17" wheels sometimes. And if I ever need to get a new rotor, I can get it from summitracing.com and bolt it onto my existing hat.

does the kit come with the spidey doll?

No, But my 10 year old was having fun. Randy if you want one I will hook you up.