OK, so I went through the annoyance of getting this mod to actually know what we're talking about here. (Seriously, if you offer a free mod, why force people to go through a checkout process and register, and in French only, no less - that just makes me pre-annoyed before even testing your mod.)
So frankly, the base experience of the mod was kinda like I expected - pretty bad. I would not consider the FFB to be good at all. It does what quite a few mods with some of these "high dynamic range" car mods do (looking at you, MakCorp Group C) - they want the FFB feel fairly heavy, but also want you to be able to feel the car, so they just crank up the FFB levels. Which, unless you have a wheel capable of direct drive wheel levels of torque output, will just leave you with FFB that is clipping all the time, so you have to lower the FFB multiplier anyway if you want to get rid of said clipping...which will basically remove all of the finer forces from the mix again, so you've gained nothing and you basically have to choose between not feeling much of the car outside of heavy wheel during cornering, or feeling the car fine, but clipping all the time (and potentially even damaging your wheel). But I guess they might not be aiming at us consumer wheel plebs anymore, I don't know.
So, as far as the FFB multiplier goes, I settled at setting somewhere around 0.5 to 0.6. It depends on how much clipping are you willing to tolerate. Even with 0.5, I was still clipping a fair bit at Spa at say Pouhon or Blanchimont, and certainly at Eau Rouge-Raidillon (which tends to be the ultimate test for clipping in simracing). But it was tolerable for me.
It also doesn't help matters that the FFB, IMO, is kinda...I don't know how to call it, maybe "grainy", or perhaps simply "too detailed". It just feels like certain details are too exaggerated, which fills the FFB full of annoying rattles and vibration, even with the multiplier set as mentioned above. What I found especially annoying was a strange vibration under braking, which rattled my wheel and also felt weird. The solution for me was to up the smoothness setting in rF2 - I generally use a setting of 4 on my T300, because I like the FFB to be a bit smoother (I know quite a few people just use 1), and I had to up the smoothness to somewhere around 8-10 for the FFB to not feel as rough.
I'm also not at all surprised about the vibration you get in the pits. There's a very strong centering force applied when the car is not moving, especially with the default 1.0 multiplier. My wheel didn't vibrate by itself, but I'd assume a less naturally dampened wheel (which I'd expect the CSL Elite would be) would probably start vibrating really easily. All it took for my wheel to get vibrating similar to the video was a slight push to get it oscillating. If that was the only issue with the FFB, I would just say try to ignore it (and don't let your wheel go when the car is stationary). But it's certainly annoying.
Finally, there's one thing I would mention. There's a FFB setting in the Controller.json file that's not available from the game UI, but I've been using it for a while to improve things especially with cars with a high dynamic range of FFB such as this mod where you have to choose between almost non-existent driving forces vs. overwhelming clipping in certain situations. That setting is called "Steering Torque Sensitivity" and by default it is set to 1. If you set it higher (2 is the max), it basically compresses the FFB dynamic range by somewhat emphasizing the low end forces and somewhat lowering the high end ones. In my experience, it can be a huge improvement for cars like this. I often go all the way to "2" with it. Bear in mind that it impacts the entire game, though, it is not vehicle dependent. So if you change it, every single car you drive will be affected. And also bear in mind that adjusting this setting will have a noticeable impact on your FFB multiplier, so you'll likely need to set it lower than normal (for example I set it around 0.5-0.55 with the S397 cars, whereas with the default torque sensitivity of 1, the ideal setting is around 0.7-0.75).
So to summarize (sorry, I'm often very long-winded) and to make a recommendation *for this particular mod* on my T300, what I would do would be:
In Controller.json, set "Steering Torque Sensitivity" to 2
In the game itself:
FFB Multiplier for the car: around 0.5 (around 0.6 if you're not changing the torque sensitivity) - should be pretty much independent of wheel, if you find the FFB too light or too strong, I would suggest adjusting the wheel's control panel instead (or the wheel settings in case of Fanatec) and leave the multiplier alone at the value I mentioned
FFB smoothness: 8-10 - partly personal preference, though also somewhat dependent on your wheel's natural dampening
Minimum force: 2.5 % - that's generally what I use, it's partly personal preference, but it's also dependent on your wheel, with the CSL Elite, you probably want to stay as low as possible to somewhat lower the oscillation at standstill
These settings gave me a much better FFB experience driving the car than the mod default with my regular settings.
Again, sorry for a long post.
