I'm looking to upgrade the fuel system on the rs6 without changing the original layout, meaning I want to use in tank pump and inline external pump. I'm trying to attain around 500whp(this is just a number) no meth, no e85, the car is equipped with a 6speed manual transmission and hybrid turbos(loba650s), currently working on a custom intake similar to Milka's build using bigger A8 MAFs and researching a good fuel setup. However I couldn't fine any technical information on the pumps, such as liters per hour at what pressure and voltage? I want to supply Bosch ev14 72lb/750cc injectors, what is our injectors size compact 40mm or standard 48mm? The question is, can I get away with upgrading just the external pump to 044/walbro 330lph(direct fit btw no adapters needed) without changing the in tank pump? Will the in tank pump provide sufficient flow to a more powerful pump?

Any input put will be greatly appreciated, even if I'm way off.