These 911R Magnesium Intake Manifolds are NOT really Magnesium! They are a "perfect" reproduction of the Porsche factory 911R Magnesium intake manifolds but cast in Aluminum instead. These manifolds were cast by Tilton Engineering years ago as a request from a "good friend". The reproduction is so good (finish and all!) that the only way I could tell was by the missing factory casting numbers and the shiny Aluminum of the scratched surface.