I don't mean that you must reduce it, only that if you need to reduce FFB strength, it's better to do it in Moza Pithouse, not in the game. Anyway, what I said is not some "magic" solution to your issue, as you can see it's basically "leave FFB strength on default in the game and adjust it on the base", and even if you do it the other way around, the difference should be practically unnoticeable as long as don't crank up Car FFB multipier so high that FFB starts clipping. You asked about Car FFB multiplier and I described how you should approach it. I hope that I can notice something in your settings, otherwise I have no clue where your issue comes from, it seems to be set up just fine. Also, what's your wheel?
After I upgraded from the simagic Mini to the Moza R25U, the level of road surface detail has improved drastically. I’m not sure whether this difference stems from the varying driver software of the two base manufacturers or the difference in torque output between the two wheel bases.