Well, this is a bit of a stab in the dark, but:
The wiring goes:
(0v) G ---- A ---- C (5v) (Pot 1)
(0v) B ---- D ---- H (5v) (Pot 2)
As the throttle body opens, Pot 1 produces a higher voltage on A, and Pot 2 produces a lower voltage on D.
When Vocky added resistors to B and C, that made Pot 1's voltage seem higher than it was, and Pot 2's voltage seem lower than it was. That would make the ECU think that the Throttle body was more open than it should have been, so it wouldn't open the throttle body as far for a given pedal position.
This is all speculation really, but it could be that as the throttle body didn't open as far, Vocky never got the dreaded P1514 - but never the full airflow of the 2.4 TB (as it wasn't fully open - it may still have been better though). All the 2.2 TBs seems to have slightly different values, and the ECU obviously does something clever as it checks how far the throttle body will close when you power it on, so maybe it adjusts a little. I was probably barking up the totally wrong tree trying to make the 2.4 tb appear exactly like a 2.2 tb to the ECU...
If anyone is interested, I can try and figure out the resistor values needed to stop the TB opening as far... It would be handy to know what codes are thrown on people's ECUs when you just plug the standard throttle body in with no resistors. It could be that it was the P1514 all along and the only way around it is to stunt the opening of the TB or fiddle with the MAP sensor.
As for fiddling with the signal from the MAP sensor, I'm not entirely happy about it either - but there seems very little you can do short of put a whole new ECU in. The Map may not be right, but it wasn't very good for modified engines anyway. With bigger injectors and the modified MAP sensor, fuelling might be ok. The thing that would worry me is that spark timing, because that definitely would be altered by the MAP sensor...