Hartge already has the product available:
http://www.hartge.de/
11 35 2306 J Engine conversion (additional ECU)
for 535i (based on 225 kW / 306 hp / engine N55B30 Twin Scroll Turbo)
266 kW (362 hp) / 5660 rpm 480 Nm (lb-ft 354) / 2950 rpm
They export a tremendous amount of their products worldwide, give them a call.