IMO, anyone quick to blame the quick rack is on the right track.
It's a great upgrade and I personally love it in all turns, but it
does add more steering effort than any of your other upgrades. I'm not surprised you are finding it a bit harder to drive tight twisties on the street, where you aren't going very fast or reaching the limits of adhesion, lifting a wheel, transferring weight, etc.
I would add some toe and camber up front to let the car rotate a little easier, but be careful that you test the result on
all the roads you plan on driving. It's pretty easy to make some small modifications at home and test-drive the result; you can always have your wrench dial it in on the rack once you show him in which direction you want to take it.
Have fun with it -- these cars are really rewarding to experiment with.
