It was a direct bolt-in affair with no mods required. All original oem connections worked as well. They did not require a core and was ~ $179.00 IIRC The only difference I noticed was that they use an oem NA alternator to rebuild to 180 amp output. The pulley shaft of the NA alternator was a different diameter than my TT alternator so I couldn't port my existing OD pulley. I went with the 'new looking' pulley that came with the alternator for the time being. Tests show it puts out ~ 14.1V on cold start-up and slowly drops to and holds at 13.8V after car has warmed up. I haven't tested/confirmed the amperage output yet.