From a performance point of view a total waste of time, you can come up with as many theory's and technical jargon as you like, but it the real world they will make no difference at all. but they do look nice.
The one you got actually looks really good and I think they work. I had one on my old mk2 golf and when you reverse of my uneven drive all the rear windows used to creak with the chassis flex, but not after the brace was fitted. How much?
I've got fun metal gray wheels on my black vr6 which is similar (less brown) and I think it looks too dark what about a nice shiny silver or even white. Maybe a pic of the wheels would help us.