Hi. I'm happy with the wheel spacers on my Ghibli. They have been on for about half a year now and do not affect tracking or handling. I went with 20mm front and 25mm rear.
(note in image below that bolts are not yet seated; they are just below the surface of the spacer when torqued down so the wheel bolts on flat - maybe obvious, but just pointing out)
I've had them installed for a few years now and it's probably one of the best visual mods you can do. I went with 18mm fronts and 20mm rears. If I could do it again, I'd probably go a tad thicker in the rear.