That’s a can of worms! Factory was metering plate. Some people like manifold vacuum. I don’t have my vacuum advance hooked up either, no problem

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"