I just bought a set of 4 - 5mm wheels spacers. They are generic and made of aluminum. They are very light and seem to be somewhat universal. They are not hubcentric but I had no problem installing them. I have et53 MY00 2.5RS wheels on the car with 225/50's. I wanted to get them out a little further so now they basically have a 48offset. I'd like to try the same thing with a lower offset wheel to see how wide I can get (ie what is the lowest offset I can fit on the car without rubbing.) I'd like to try some et48 wheels like Rota's with the spacers which should result in a 43offset. With the lug nuts I have there would not be much room to go anywider with spacers without safety issues.
Anyways, after installing there is hardly any noticeable difference but they do hug the fenders a little more. It may be more noticeable if the car was lowered. But 1cm total is not much.
They were $5USD a piece so a fairly cheap mod.