Well, when my brothers engine had bone stock unported Edelbrock heads and a old school Mopar .557 mechanical cam it made 513 horsepower on a DTS dyno with pump gas and 1 3/4 headers. It was only 394" using a 3.79" stroke crank. We also used a Mopar single plane M1 manifold. Our carb was pretty trick though. It made more power than ANY of the trick carbs that our Dyno shop had on tap. They were pretty amazed. We have PC Carbs in Ontario California do our carbs.