Understeer is the most common issue with new autocrossers and no matter how the car is setup, most people--even veterans, will want to overdrive the car into corners.
You have a swaybar in front that I think is too stiff (it's solid as I recall) and uses a short endlink position as well. I use a 35mm hollow and the softest hole makes for a longer lever arm. So my front bar can be a little softer to a touch stiffer to give you flexibility in tuning. And fwiw, my rear bar is also 3 way adjustable.
You are likely lacking negative camber which would help the car turn. You are on a mis-matched set of tires too which isn't likely to help--and someone said it before, the rears might be stickier than the fronts as well.
In short there are many things that would help, both with the car and the driving. I sell parts, and I teach autocrossing too. I don't sell parts with the idea that they will fix every ill, they can't fix hair-on-fire driving.... but on the the other hand, a car that behaves better is easier to drive and makes people less prone to trying to force the car to do certain things.
Frankly, I'd have to say you want to start not with Koni's (which is in itself odd for me to say) but with a different set of swaybars, and possibly a set of Steeda HD mounts for the front. You have decent, if not great dampers already and if you were to spend money on a shock change, I'd have to say that the Koni move would be better with Sports or even a set of Tokico D-specs to give you some tuning options that your current stuff, or STR.T's don't offer.
And finally. No on the torque arm. It will not help you, and in fact it adds a lot of weight to the car, and a 3-link works great. In fact I have a Camaro and if I could swap it to a 3-link, I would in a NY Minute. Besides none of your issues are to do with what a torque arm does anyway.
i wasnt gonna say anything man ha ha ha ha
