Not surprised someone asked, it more simple than you could imagine. The area behind the fuel pump diaphragm is ventilated to the atmosphere, to prevent pressure build up from changing the static pressure. So, when you run a vacuum-less boost line to it, it increases the pressure at the diaphragm.
It increases almost 1 to 1, someone did the math on it and it's actually like .97 to 1 or something, but it's pretty damn close. It only works to about ten psi, after that the fuel pump can't keep up. But with the intercooler now I should be maxing out at about 10 to 11 psi.
Also, demons like about 8 to 8.5 at idle, so it'll be right. And I'll be up at around 18 to 19 psi max boost.
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I <3 forced induction.
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