The welding was to make it a sq. flange opening. my porter said this would be a better intake than the vic , wants me to run a 2in spacer. carb is a 4150. i also have a 750 that flows 1036 gas carb i will try. 3300 is with me in it, car ran 11.70/11.80's with a mp 557 cam, same intake unported...