DX Diesel Xtreme is our newest heads on the market. It is taking the diesel market to places it has never been before. An aluminum version of what has always been a cast iron cylinder head. They’re now lighter and stronger than it’s cast iron brother and has been tested for the past 12 months, in real-world testing. We have strengthened many areas and made many power and flow improvements for out of the box gains. These heads also feature 356 T6 aluminum and are machined and assembled in the USA.