Based upon Shag going from a Holley 750 DP to a 650 DP and then to a 650 vacumn secondary carb, so far I have gone from 10.5 mpg to 14.5 mpg and this is after driving to the coast to have lunch with Opentracker with Abe as being the co pilot and then back home via the mountains. I think with the upcoming trip to knotts this weekend which is basically very flat I should be able to improve the mileage even better.