I've found the Lister to be quite understeery, apart from when starting to slidePS noticed your setup is "flat ride", was that intentional or just an accident of the setup.
So I raised the rear wing to get more grip but lowered the front suspension a click to get more grip through slow corners.
I guess in reality these cars are meant to be slightly drifted with the 50%+ power diff, but I can't control that at all, so prefer an agile suspension setup with stable aero and a very low power diff