Over the years I have basicly run carbs that were way bigger than most methods would work out---and the basic reason??????? well , they have been on trucks that I used to tow the real race cars---------and I wanted a set up that would give me more air on just midrange primaries for highway speeds ( 70-75 mph) without getting into the seconaries on the carbs----------had lots of discussions with the folks at Edelbrock( they balanced our California Charger dragster engines back in early 70s) there methods of sizing was for wide open max rpm areas and would just have a 600 cfm--------I ran an 800-850 that would give almost 400 cfm before sec opened-------I got 9-12 mpg whereas those smaller more effienct 600 carbs would only get around 6 mpg--------