I cannot quantify the speed gap between 2 cars during an overtaking

[Deleted member 1031992]

I am currently trying to mod F1 2021 with realistic data.

Dirty air is ok with -74.49% downforce in the wake of a single-seater.

Now, I am trying to modify the intensity of the slipstream without DRS and with DRS but I cannot find any data on this subject allowing to quantify the difference in speed between 2 single-seaters during an overtaking on a long straight line.