My Hotchkis sways and Whiteline rear endlinks are here. I have a 2009 G37X. The front sway bar has two holes. Which one do people use and why? I'm going with the middle on the rear. Thanks

 

The settings adjust the stiffness of each bar. Closer to the bar ends means less stiff on that axle.

If you want to reduce understeer, you stiffen the rear and/or soften the front
If you want to reduce oversteer, you stiffen the front and/or soften the rear

The combination of front and rear settings is really what matters, so I think your starting point makes sense. If you feel the car is still understeering too much, go to the stiffer setting on the rear. If instead it's too oversteery, try the stiffer front setting.

 

Is this an X bar thing? My front bar is not adjustable.