This script really solved all the caveats of playing with an gamepad for me.
But the recommended settings makes the car very unresponsive, "understeery", and just too "heavy" for me.
I use the following ones, and it works wonders for all cars I've tried (Citroen DS3 WRC, Ferrari 488 GT3, RSS F1 2021, Porsche Cayman Turbo S and McLaren P1 GTR):
Speed sensitivity: 70%
Steering speed: 1%
Steering gamma: 100-200% (Higher values makes the car easier on corner entries, but more understeery. I use 125%)
Steering Filter: 0%
Steering deadzone: 0%
This makes the cars way easier to drive, while still allowing to get close to the limits of the cars. The McLaren P1 GTR is way more manageable with this script and a very fun drive.
Edit the lua file, and decrease the reboundSpeed value to slow it and vice versa.
I know not all of us are keen on editing source files but until Content Manager gets a way of editing variables in lua scripts that's the only way.