The springs make a huge difference! We just put 'em on on Monday, so they're still settling, but the ride is much better (obviously much much better thru turns). I took a left turn yesterday at around 35-40 to beat the light & not a peep out of the tires, it feels solid & no slipping... It also seems to help reduce any forward pitch when braking or shifting. Next up will be the rear sway bar to get rid of body roll... unfortunately strut tower bar is n/a right now as you probably read.
I didn't see IIP on a tC until I picked up my car. I decided on the color when I saw it on an xA in and out of the sun. The difference is great... nice and dark in the shade & all sorts of different shades in the light