An inline pump will work fine for what you are trying to fix. (on a return style fuel system that is) I think an inline pump with a stock pump will actually flow more fuel at 58 lbs then just a 255lph in the tank pump.

Pumps are rated at a specific pressure ( about 43 lbs I believe) and if you are below that pressure, they are actually capable of flowing more volume. With 2 pumps in series like that, you are splitting the pressure duty between the 2 pumps (about 29 psi each) there for increasing the flow rating of both pumps. With that in mind, a stock pump should flow more then enough fuel to keep up with your fuel demands, and the aftermarket inline pump will keep the pressure where you need it. Make since?

If I did it over again, I would keep the stock pump in my truck and add a booster pump, to help maintain the functionality of the stock fuel bucket. I haven't had any problems with mine when low on fuel, just looking back in hind sight.

 

i have stock intank, radix supplied inline and with mods I am at 103% duty cycle on both the 1-2shift and 2-3 shift. Plenty of pressure...66+ but going lean at the top of the rpm bands. that's with their 43lbers.

 

Would a Radix intank work for us guys with return style fuel system? Or did they just do that for the returnless style fuel system guys?

 

Bigger injectors should fix that.

 

Better to leave the OEM fuel module intact and just add the inline if you can. In-tank is the only option for returnless.

Here's a link to some testing with/without an inline booster. Looks like the primary determinant of total flow is the capacity of the booster pump. The total flow in this case was a little more than the flow of the booster alone.