Have anyone seen or have that yellow Nissan skyline brake caliper kit from ebay? I am having a hard time finding it, anyone have it? how was it? fits stock 18" wheel?

 

Without looking up any of the numbers, my recollection of Skyline stuff vs. RX-8 stuff is that this would be overamplified for the front of the RX-8. If that's correct, then you'd be asking more of the front tires, and braking distances would actually increase, because the front contact patches would reach saturation before the rears. You'd get more pedal travel, in spite of any increase in caliper stiffness, due to the increased fluid displacement requirement. But it would definitely look cool...