In actual fact the Weber ECU's can cope with Modern injectors but the
software in them cannot !!!
I have a program for a L6 that controls 700cc Jap injectors lovely but not yet
dyno proven as I have put all my effort into my own ECU.

I (and others) have had good results from 700cc Jap injectors (greys are 550cc)
and on pump fuel, these theoretically can give around 520 BHP
with excellent emmissions control (subject to port sizes).