I've been using this little valve for some time to keep the Boost pressure from the regulator till roughly 11psi for some time- it really helps!
http://www.automationdirect.com/adc/Shopping/Catalog/Pneumatic_Components/Pneumatic_Valves_-a-_Accessories/Air_Pilot_Valves/AVS-5241
I have some on the shelf , $25 with fittings or you can buy from the link above for $15.50.
Pressure in goes to P and the pilot, and there are some plugs needed because its a 5-way valve I'll post pics and instructions later.
http://www.automationdirect.com/adc/Shopping/Catalog/Pneumatic_Components/Pneumatic_Valves_-a-_Accessories/Air_Pilot_Valves/AVS-5241
I have some on the shelf , $25 with fittings or you can buy from the link above for $15.50.
Pressure in goes to P and the pilot, and there are some plugs needed because its a 5-way valve I'll post pics and instructions later.