@IaM-Ray we use an Aeromotive A1000-6 regulator with return for 06/07 based EJ253 motors.
Some Suby motors have a built in regulator in the stock rail/fuel system and an external is not necessary."
Thanks @chines1 learn something new everyday on these cars, I am not sure I have a regulator at all on my car I will check but I am not sure if I would recognize it so I will investigate.