They don't run rich at all really if you think about it.
You sure about that?

If you have HP Tuner go read the ADD vs RPM table, look at the numbers.

At 0 seconds into PE and at 4200 RPM, it will take away -1.2 from the base AFR, that is already 11-11.2 afr, give it 6-8 more seconds and raise the RPM by 1200-1400 to nearly 5500 rpm and it will take away -1.5 from the base AFR, you are now below 11 commanded AFR. 10.7 to 10.9 atleast.

Thats sounds pretty rich to me, it can go even richer and be sub 10's if you lay into it for lng enough.

No matter what you really do and because when these cars shift and don't drop huge amount of rpm during the shift you are always going to running near 11 afr if not slighly lower.