I've just returned home after being away for a while.
I did a search and found these tips buried in our Forum, so maybe these include the info you were looking for.
Definitely you should do step 2. Not sure if it helps FFB but I'm advised it is necessary to improve controller response with a wheel.
If you modify the Physics file as per item 4, it will increase FFB. However, I haven't found it necessary with my Fanatec GT3. Also, please note that it will only work with default RBR, if you use RSRBR2012, the Physics file is rewritten to default RSRBR settings to prevent on-line cheating.
1.Go into your RBR folder, usually located in C:/ProgramFiles/SCi Games/RBR and find the file RichardBurnsRally.ini, open this up in notepad, and delete the top line that says ConstantForceMultiplayer = ... (wise to make a backup of this file just incase it doesn't work for you).
2.Rename PC_Inputfilter.ini to PC_Inputfilter.bak or delete completely.
3.When ingame turn under filter settings, on steering filters turn curvature off on both lines and also turn Fade off. Do this for digital filters too.
4. If still not enough FFB open the Physics.rbz with winzip and extract the file physics.lsp. Open this with notepad and search for the line (CTRL+F) MaxFFTorque. Default is 130 i think, for more FFB set to a lower number, i have mine on 90.
Press CTRL+S to save then open the physics.rbz file up again and import/drag the new physics.lsp into physics.rbz
I use a GT3 wheel and find the FFB pretty strong.
I have my FFB Strength setting in RBR Options at about half way, anything more seems too much for me. I then adjust / fine tune the FFB using the wheels setting adjustment on the wheel (the led settings). Under FFB I use 30% but if you want more, just increase it there.
For RBR, I also find the GT3 wheel too stiff / heavy for quick reactions to oversteering etc, so I have to use some Drift Setting (usually about 003). This lightens the wheel.
Hope this helps a bit.
EDIT: As noted by WorkerBee above, make sure you have RBR Official Patch 1.02 installed.