I changed my FFB from 3 to 1 and have been improving my times ever since. I also have it set to simulation with PS on. Seems to work for me which is weird because when I used to run all my NASCAR races, I had the FFB set at 8 and couldn't stand it any lower.
I might be wrong here but I don't think that the simulation settings do anything at all for the G 25/27 wheels as the bottom right three are the only ones that are "highlighted" when making these options. I do set mine to sim but haven't noticed any differences in any settings for this.
BWXThe power steering does do something... it wrecks the force feedback, well for me it does.