Originally Posted by jdereu
So what's the major benefits of both of them. What does fuel going back to the tank allow to happen
Fuel going back to the tank will allow air in the fuel rails an alternative route to escape instead of being forced through the injectors. This will increase injector life and quiet down the engine some.
The major benefit to both of them is that they will stop the #8 injector's starvation of fuel. Since #6 fires right before #8, with a stock fuel system the #8 injector does not get the fuel supply it needs because the fuel rail is a dead end design that ends at that injector. Letting fuel flow freely through the rails is what ends this issue.
The main benefit of the full regulated return is the bigger lines used. This lets more fuel flow.