I'm not sure how 1 psi would make a tremendous amount of difference in the whole sche,e of things. Would it be worth it to decrease 1/2 psi? I don't know of an Ikeric pump, or the benefits of a design with such a low pressure.

To answer your question, you can design your own manifold assembly as the components are available through your AutoPilot dealer as a special order.
So it is possible. But worth it? In my opinion, most likely not.