i doubt that very much iam sure you would still see a improvement say using ians manifold than a standard ford one even at standard boost pressures as it has velocity stacks a far more smoother inlet and headers , plus the inlet plate is tappered which all helps improving the flow , have you ever put your hand inside of a standard manifold? they are rough as fuck. i will be honest though and say these manifolds come into there own at 20psi+ and i will also say how many people run standard boost? not many i think lol

cheers paul