go right to porting. Grind at them until there is no evidence that they ever existed. This will leave you with shiny metal that you can make legible marks. If you havent yet read the article on basic porting, please do so before making one of these manifolds your first attempt at porting. Cylinders 1, 2, and 4 will be fairly straight forward. For a NPT port, drill to 7/16. They dont get in my way while porting, I usually have to mill this surface anyways, plus I install new ones later. Tech Lines Color Guard coatings require a touch up sprayer to apply. After all of the porting and machining is done, kortingsbon rolgordijnwinkel I like to put the manifold in the oven at 400 degrees for about a half hour. There is a clearance notch for easier access to the nut that holds the manifold to the head.