These MAC headers for the 1979-1993 Mustang with a 351 Windsor Swap V8 have 1 3/4" primaries and 3" collectors, are made from 16 gauge steel with single port flanges to prevent loosening that may occur with a flame cut solid flange. MAC's True Fit collectors eliminate gaskets which are prone to leak. All MAC headers retain emissions controls and come with threaded flanges, machined steel studs & locking flange nuts.
Note: For Trick Flow Specialties Hi-Port Heads. Fits 5 Speed transmission only