Good grief!

Ok, your last car had a fuel pressure regulator. You have to have one in order to make fuel pressure period. Otherwise you'd just be splashing the injectors with fuel and it'd be blasting back into the tank full force.

All the fuel pressure regulator does is set the base fuel pressure. It's referenced to the manifold pressure to keep the pressure difference the same. Ie. if you're boosting 14psi, the regulator adds 14psi of fuel pressure so that the difference between the rail and the manifold is always the same. And adjustable regulator just lets you change the base fuel pressure. Just use your stock regulator.

I mean, yes fuel pressure regulators are magic. The government doesn't want you to find out about them because they add hp and gas mileage. That's why Nissans are so fast and good on gas. Your build should have of them!