Right or wrong, I made a adapter for my bench to bolt the carb pad to then duct tape closed all the runners except the one I am working on. I do most of my work with it pulling on the runner but also push through it at times along the way also. That being said though I run an unported m1 on a stock headed 509 cam 10 to one 440 and its been low 11.20's with a 750 double pumper and a 2 inch spacer. I think the intake works pretty good. I say just gasket match it and run it. I also agree that no mater how good the intake is, it has always cut flow of the head. Some less than others but still did.