We designed these valve seat inserts with porting in mind. Because of their extra thickness, when installed their 30 degree top angle will extend all the way to the combustion chamber edge for a nice transition eliminating that ‘dropped in a hole’ look that robs flow. Their outward inside taper aids in blending the seat to the port wall and their radiused outside bottom edge makes for easier installations by eliminating galling. The outside diameters are large enough to ensure that you are boring into all new metal when over size machining the old seat pockets for their installation.