What John said here would be interesting if it were possible: "But, theoretically, the ECU could use the pressure sensor to control the regulator, but I'd have to see the wiring diagrams to find out if that's even possible"

John suggested "Personally, If I had a B6, I'd buy the return lines, fuel pump, etc, the V6 used, and install a FPR up front"

what would I do about ecu?

There are others making plenty of power with the stock non return fuel setup.

"If I had a DBW, I'd switch it over to nonDBW"

or something to that affect :)

keep in mind the regulator is probably built into the pump assembly.