Holley/Demon Carb stumble

Probably not.
EFI to Carb Dual Stage Fuel Pressure Regulator – Aeromotive, Inc

That's a one "big price tag" to control pump pressure to 16 and carb pressure to 9
The first stage will get it down to 9 psi. just like mine............. Just saying.

• Controls pump/line pressure from 8-16 PSI.
• Controls carburetor pressure from 5-9 PSI.