No. 'Returnless' is shorthand for not referenced to manifold pressure. It has nothing to do with how many fuel hoses there are or where the regulator...
And I know this might sound crazy, but have you tried... going back to an earlier version of the tune file, before you started messin' with stuff and...
The injectors are still the stock L59 injectors, if by "returnless" you are referring to a fuel line returning the excess pressure back to the tank I...
The regulator has no vacuum reference, and the mechanical gauge is on the regulator and is set to 58 PSI I will insert the link directly to Holley so...