@yellow rose ...Correct for what type of driving: drags cruising...mileage? How many iterations of timing curves were changed over the years of a slant, like every year it was different? The ability to change X when Y
and Z changes is nice to extract the last tenth, ft/lb or MPG. Locked out distributors are nice for racing, vacuum is nice for the street. Have both curves advantages depending on engine demand. You can do this (to an extent, no MAP inputs) with the latest active distributors from MSD as well as adapting a locked out electronic ( ie. lean burn) distributor with Mega-Jolt and Micro-Jolt controllers without the EFI system.