I think the Wildwood based kit fits under 16" wheels - and maybe the Porsche kit also. Remember the skyline kit has the same pad/rotor area - just thicker rotors. So the only real effect is decreased fade (not to minimize this but it takes some spirited driving to tell the difference from just upgraded pads/rotors). I think you overpay for the Skyline kit b/c you are paying Nissans inflated caliper prices.