OK Can't find good figures for the 3.5 MB V6, lots of MB seem to use 18 lbs / hr but no indication of pressure. 3.6l V6 using 0-280-155-758 should be 19 lbs/hr at 43.5 psi so bit more, perhaps 21.5 lbs/hr at 55 psi.

Base line for injector flows is usually 43.5 psi (3 BAR) and the Crossfire NA runs 15.1 lbs/hr at that. You need HIGH impedance injectors (very important or you will fry an ECU).

BMW 6 series 2.8l supposedly has Bosch 0-280-150-440 High impedance which would run about 25 lbs/hr at 55 psi. BMW look the best bet for close but a little bigger, but the info available is sketchy on most models. 3l and 3.5l might also be OK but the base or operating pressure is missing.

Most important thing is impedance is high (usually 12 to 16 ohms).