Lots of bad info out there.
A properly tuned DP will NOT get worse mileage than a performance choking vacuum secondary carb. Most of the mileage is how you use your right foot!
A vacuum secondary carb is friendlier on the streets than a DP. The DP was designed for racing, not cruising. That's where it performs best.
The VS carb was designed for street use. There is nothing wrong with putting one on the street.
Total hp with properly tuned VS and DP carbs of the same size will not be appreciably different. The differences will be noticed during aggressive throttle movements.
The power difference I referred to would be between different size carbs.
