This has been discussed on the mk5 section and the consensus seems to be the OEM tinted windows are best since it's actually the glass that is tinted, rather than a film on the glass. You can buy them from a dealer and get them fitted, as far as I know. The main problem with the mk5 and tint film is that it can't fit into some of the curves well, most noticeably on the rear window where you will have white line at the bottom where the tint film won't fit.