Years ago, a guy I know used to acid port heads to increase flow on "stocker" heads where porting was not allowed. No one ever caught him at it.





There was a lot of that done when I raced on dirt. Somewhat even removal of material inside ports with most of the original casting character maintained. Many a tech man got hosed! The fellow local to me who had the most experience with this has since passed on.

...FAFO...