Ok. So I got some bad info. I know a regulated return keeps a constant pressure to all injectors by regulating pressure after the injectors. Question to you is what makes the FRX beneficial to you fuel system? From what I've read it has small ports allowing fuel to return to the regulator while still using the factory pre injector regulator. Correct me if I'm wrong on how it works. So if there is no air in the system why use it? I know a regulated return you have constant pressure to all injectors but the FRX would still be able to starve the end injectors correct?
A RR or even a factory setup still maintains a set pressure.
I don't use the FRx hose. I personally hate to hose anything as it looks messy, but sometimes you have no choice. And the price csn dictate that.
What the RR and FRx does is just moves the pressure relief (regulator) to a different spot in the circuit. Instead of right at the bowl on a factory system it can't bleed off as soon as it entered the bowl. So it forces the fuel into a different route. That's how it helps to not let the opposite end injectors starve. A RR does a better/cleaner look to move the pressure relief further back in the circuit than the FRx.
Here's the biggest drawback of the factory setup. The factory fittings in the heads have a tiny ball-check in them plus a screen mesh. These dumb things dramatically reduce flow and cause air in the system. (Just like that screen on your kitchen faucet).
On a RR, a 3/8" line is used to feed the back of the heads. Which is fine in itself, but also pointless because the port in the back is still only 1/8" pipe fitting (still somewhat restricted). You can only push X amount of fuel at X amount of pressure through such a small hole. A four line feed will balance the pressure throughout the heads regardless and give you double the possible flow over a RR if needed. In our race truck, its needed.
FYI, I do have a significant amount of run time on both systems I make with different HP setups too.