4 words: The feel is amazing!!!
In the demo version of PCars 2, I wasn't happy with the feedback I was getting on my T150, it was very dull and not pronounced at all, unlike AC or RF2, where the cars feel tight and responsive.
I watched SimRacing604's video recommending this FFB file, saying some even compared this to RF2, so I bought the game and went straight ahead and installed this file. I didn't even bother using the game's preset, because I gave it a try on the demo.
I'm on my second day trying out PCars, most of the cars I've tried so far (G.C, GT1, Formula Renault etc.) were totally fine, but on the Kart, the wheel vibrates like crazy when I'm not turning the wheel. Perhaps some deadzone or minimum torque issue? I'm not quite sure how to fix it.
A kart hasn't got suspension but rather it flexes, and controlling that flex in a kart determines its handling characteristics.
Sadly the game doesn't use a flexible chassis model but rather uses solid chassis design instead. Not impactful on modern cars with stiff chassis, but older cars and especially karts could use chassis flex.
In the end this meant they had to try some suspension geometry and setup trickery to approximate the characteristics of chassis flex. Sadly this didn't work out well, as you see.
My recommendation is to get Kartkraft for some proper karting simulation, and just use Project C.A.R.S. 2 for the rest it offers.
So it isn't due to the file, it is just that the file exposes the flaws more in those karts. Sorry. Wish I could do something about it.