In some cases, the port on the header will be larger, or a different shape, than the port on the head. This does not mean that it is the wrong header. Many headers for D-shaped exhaust ports have round or oval shaped ports.
As long as the header flange does not cover up the exhaust port and there is enough surface area for the gasket to seal, the headers will work.
- Follow this link to learn more about The Header Flange.
Notes
- DO NOT port-match the cylinder head to the header. Exhaust Reversion will result.