I did a few more checks, and saw indeed a difference between my installs.
Top speed at Imalo is indeed around 350kph on a stock install (so it is faster than GP3), but the cars struggle to reach it. The thing that seems weird at the very beginning with my modded install was that the AI cars were hitting the rev limiter on the tracks I tested: Nurb, Silverstone, Monza. (354kph on monza)
What was really stunning was that the cars didn't seems to be slowed down by the air: on monza after 340kmh the counter was still going up quite fast, until the rev limiter was reached.
My issue came from the .dat files of the tracks. I replaced the .dat with the original ones, and the issue disappeared. (while keeping the wad)
So my questions are : what is in the .dat files ? How can I see its contents ? Can I use a upgraded .wad and the original .dat ? It seems to works, but i'm wondering if i'm going to have issues with racing lines, or grip values.
Edited 2 time(s). Last edit at 08/28/2021 11:05AM by zifox.