K sport= POS there just for show, rx7 could be the cheapest if u bought everything second hand but bit of a dick around to find all the parts and rebuild the calipers, wilwood would be easy as they come with everything just have to bolt it all together, i think u can tell them to change or leave out the disks as there cross drilled, they might not crack with ae86s being so light but cross drilling looks gay. With all of these i think u would need a bnr32 brake booster as well as upgrade the rears to balance it out a bit ,r31 diff or u can get these plates that u can bolt a twin caliper set up and think they use skyline disks and calipers i think. Never ownd any of these nor felt the need to up grade the brakes these are just my observations