I've been asked a lot of questions about the centre caps so I'll clear this up for good!
If you have 17" straights and want to remove the OEM centre caps, you'll need these...
http://www.ebay.co.uk/itm/1412177565...84.m1439.l2649
...They are the standard 65mm VW centre caps - but they won't fit first time. I'm definitely not one to bodge things, but they seem to be about 1 or 2mm to small for the center hole on the alloy. A simple way around this is to wrap some electrical tape around the lugs on the inner bit of the centre cap, apply a small amount of mastic onto the tape and then push the centre cap through the centre bore hole in the alloy. It's then a nice tight fit and fully secured.
For the decals, you can stick these straight over the VW centre caps and they are a perfect fit...
http://www.ebay.co.uk/itm/1609277242...84.m1439.l2649
...these are what I used, but any 60mm decal will do depending on your preference of course! You need to apply these with a hair dryer though to make them more pliable, as they need to be curved around the centre cap. Took me about 10mins to do the whole lot and well pleased to be honest!