I need to know, how you came to the conclusion that 14psi is the equivelent of atmospheric pressure x2...
Atmospheric pressure = 1 bar
1 bar boost = 1barg (gauge) or 2bara (absolute)
I do agree with Grant that the technical knowledge in here is a little 'bloke down the pub' - as proven above. I'd recommend eductating yourself before making your own judgments based on facts divulged on the various websites, here, SNet, 22B etc.
My thoughts on dump valves are pretty well documented on here, i see you have a flamer kit fitted already though so will leave you to screw up your cars fuelling on your own.