Disc Brake UPGRADE KIT: Performance Front Brake - 82-92 FIf you have a 82 92 Firebird, Trans Ams or Camaro.. some people find the brakes a bit lacking.. This kit is for most all 82 87 & some 87 92 that did not have the 12 inch larger again rotors and "Performance Brake" package (see NOTE below) If checking.. you will have 11 inch Front disc rotors.. . thats very very close to 27. 9cm If this is your concern OR.. or.. if you just want to greatly increase the brake effectiveness start HERE.. and do it right..