Cheers mate
The Cupra R splitter fits more or less straight on, but there are two pillars/clips in the middle (see pic) that are a bit too tall, but they are easily chopped down with a stanley knife, then you just have to screw the splitter into the bumper (I think it clips on to the Cupra R bumper without screws).
These are the wind deflectors I got (from seller eternalcar), they are the decent Heko ones.
http://cgi.ebay.co.uk/SEAT-LEON-4-5...arts_Vehicles_CarParts_SM?hash=item2e9f64ead9
Yeah they would look really good with smoked windows to match.