I don't know what a-b-d means, but @sby has written a penisrange mod which significantly extends the slider range.would like if someone could make a swf mod that doubles the langth of the dick a-b-d from its largest size.
The current throat expansion behavior is a compromise. The full neck is capable of stretching, but it doesn't do so unless presented with an absurdly large penis -- one which completely dislocates the jaw and introduces obvious visual flaws into the game. Hence, stretching is effectively limited to the upper neck. We could tweak the code to make the neck more "responsive", but this carries its own set of problems.as well as making the throat expand all the way down rather than just below the jaw.