Yeah you are right, some of the fantastic looking mods are overpowered, grippier, stiffer and not easy to keep up during a quick race or track day ride then the similar class cars... You can edit the power output by unpacking data file and changing values in drivetrain, engine and power scripts in data file and repacking them. But it's not always easy to retune to realistic specs in this case reduce power....Also at physics department (suspension, grip, ffb, bodyroll) I can only say to compare it with similar cars datas which you think are more realistic, watching real-life review and driving videos and doing some trail-error tests which in my opinion needs more experience which I cannot invest enough time yet. If you can reach out this guy did good physics updates and try to learn more but he is not around for a while :
https://www.youtube.com/channel/UCMOFM8OEKoRVgf2APXb157g/videos
There are also some modders good at physics on facebook where this mod released...Tell them about yoıu opinion
Same modder released a BMW M2 few hours a go...again same situation..even stock 2015 M2 is as fast as a Ferrari 458 Italia.. I hope they realise this situation and do something...