The setup seems ok as well as the physics on XRG and FBM, so far the thing is the controls configuration, as already mentioned by Draggo and on XFG the Wheels are still the stock ones instead of custom ones like XRG and FBM.
Come on chase... don't be so radical, the car it self is an pretty amazing build! Sure if you said that those videos are some kind of boring and stuff I would agree, but not the car. Go here and see some of the work done to the car, it's amazing! http://www.speedhunters.com/2014/11/gymkhana-supersta...
That is why some of the s-chassis have some kind of body kit, however tweaking the wheel base to de correct position (longer and narrower) is an option, I've done it with my s13 and it didn't perform that bad at all, although I can't have a great sense of that because I use a mouse+keyboard to drive...