This is exactly what I've been looking for, thank you! Works great on my G923. The default and other custom FFBs had that annoying rattling in the center, that's gone now and makes the game much more enjoyable. You can really crank up FX to 100, my gain is at 86, damping and LFB on 0. Feels great for me in every car I tested.
I think G923 owners should stay away from all the G29 custom FFB files. Correct me if I'm wrong, but what I've experienced and read somewhere is that the G29 and the G923 (maybe also the G920) have a different deadzone in the center. So more FX in the center are maybe fine for G29 but not for G923. I think Logitech was trying to give the G923 a bit more FFB details but the center rattling made it feel a bit like a toy.