I have 7 mm front and 15 mm rear. I think they definitely improve the looks, and, according to a couple of knowledgeable folks, SHOULD improve things on the track. We'll see, since I'm going to a DE next Sat.
I have 17" wheels on my 01. How would adding these spacers increase any suspension stress over what increasing the wheel size to 18's and the tire size accordingly? Or what additional stress would simply increasing the width of the tire do???. I could put on 18's, which was an available size from the factory, and be at approximately the same relative position in the wheel well as putting on the spacers. I'm not convinced that any additional stress results over what the factory has allowed for in the design.
Now if we're talking about 50 MM spacers.. that's another matter! but the 7 and 15's are actually pretty small.
Just my .02
Bob