Actually I personally wouldn't use my sway bars to tune in the understeer, I Would use my toe angle and set it for 1/16 total toe in with a neutral sway bar set up. You can still box your suspension bracing up top and running a nuetral sway bar set up wont directly effect the lower suspension as much as you think. Grip starts at the tires, so your suspension reacts/affects the car from the bottom up not the other way around. Also take into consideration that your running wider/lower offset wheels than factory, and this affects your scrub angle/ bump steer sensitivity, at speed I would want no understeer and having the turn in intiated with the toe angle, so at the enertia transfer to the outside tires the car sticks like gum to your shoe( like mine :p).Just my 2 cents
Front toe : 1/16 total in
Rear toe : 0
Front camber : -1.5
Rear camber -1
Yes I see where you would deffinately be comfortable swapping in stiff springs for he rear, especially with your taste in aero going fast you should feel quite planted.
Man I'm so excited a out getting a bucket seat!! Thank you for letting me know about those!!