Downgrade you Fanatec firmware from default 681 to 669U.
Than use this settings for GT5 exclusivelly:
Sensitivity (SEn): 0 (when on "0" it actually uses game settings for steering degrees)
Force feedback strength (FF): 90
Vibration strength (Sho): 20
Drift mode (dri): 5 > most important setting*
ABS: 25 (I use 25, because I like to feel rumble early)
Linearity (Lin): 0
Deadzone (dEA): 0
* for write up why "Drift" setting is extremely important and why you should downgrade to 669U please visit this writeup I happen to elaborate and wrote today after few months of GT2 testing:
http://www.neogaf.com/forum/showpost.php?p=28638767&postcount=1931
If you can manage to run 1.04 on Tsukuba with stock 111R and on default GT2, your driving is more than good.
Cheers 👍