I've used brand X return line adjustable pressure regulator for fuel injected turbo cars that I modified to suit for Cummins pressure range. I'm using boost reference. Basic pressure is 30 psi with non to low boost and above 15 psi of boost the fuel press gets up to 40 psi. Has worked flawlessly now for well over a year within big temperature variations, +35 Celsius during summer and -27 Celsius during winter.