2004-2006 Cadillac CTSV headers.  1 3/4" primary tubes with 3" od collectors-headers only.  Long tube design makes great power and mid range torque.  3/8" s/s CNC laser cut flanges are port matched to the cylinder head for optimal flow and maximum performance.  Will require cutting, welding and fabricating to connect to stock or aftermarket exhaust systems.   A Stainless Works product.