Mine doesn't do this. I can easily modulate the shift points by throttle position. It has a pretty big range from 5%-10% throttle up through 50% for normal driving. Above 50% it's generally all the way for me .

What happens if you leave it in sport mode? Don't you get to higher gears later?

Not sure what the 4.6 shift points did but I'm pretty happy with my trans with the exception that from time to time on 50% throttle positon shifts it can be a bit uneven, it's harsh from 2-3. Not always but sometimes.