As the suspension nearly stays the same, respectively will not allow new geometries or damping character, there will not be a change speed wise. The TC6.1 is still on the same speed level as every other (brand new) TC out there.
What will happen is a more constant behavior, allowing us drivers to get closer to the absolute limit on a full heat. Something similar that happened 2010 with the model change from TC5 to TC6.
AE / Reedy / RSD