I have a 65 Ranchero, 200 -6. 68 Mustang dizzy recurved with with softer springs, I bent 1 tab on the spring to increase the mechanical advance. I ru about 14 degrees initial advance. Autolite 1100 with the spark control plugged off, run ported advance , rejetted the carb from 56 down 50. Number 1 and 6 plugs 1 range cooler , all plugs light tan. Runs very clean, timing set for no ping on a hill. Fuel mileage at steady 65 on highway about no better than before all this change. Car still feels somewhat sluggish. All I can figure is that I still do not have enough mechanical advance. What do the experts say? Thank you.