FWIW, carb tune is VERY important and it will vary between engines as well as individual intakes. Similar to the above comparison, I did try to optimize a 4779 750 DP and a 3310 750 vacuum on my race car. The DP was about .10 faster. I don't recall the mph, but I'm sure that was a bit faster as well. A 4777 650 DP ET was about the same as the 3310 750 vacuum. A DP can be made to leave harder than a vacuum carb in most cases.