So was it confirmed that the M42 injectors are 20.5#/hr?  The PN is still the same as the M30 injectors, and I am really sure those are 17#/hr.  I put in the S50 ones at 17.5#/hr, and it is running just fine, even a little smoother than before.  It would be running really lean if I went from 20.5 to 17.5.