Just modify a line in each team's .VEH files. For example, I'm going to modify ALPINE's performance. Go to the folder "GameData\Vehicles\F_V10\NC2023 Alpine" and you'll have two files called (01Alpine.veh and 02Alpine.veh). Now just open the file with NOTEPAD and edit the line (Upgrades=F_V10_upgrades_02.ini). Replace "02" with numbers from 00 to 05. The performances go from (00 to 05)