I tried changing the injector scaling this weekend. My first go was wrong, I had not noticed that the value shown in Romraider is inversely proportional to the ROM value, so I divided it instead of multiplying it.
The second attempt to increase it brought me to the realisation that the injector scaling cannot be more than doubled from the stock value (it hits the max for a 16 bit value). The ROM I wrote with the anti lag injector scaling maxed to 0xFFFF didn't run for more than a few seconds (I must have broken something else in the ROM since the car was going off before that code was activated). I then run out of time to do more testing.
I think I'll have to look deeper into the overrun fuelling code and find out how fueling is decided then since adjusting the injector scalar will not yield much more fuel anyway.