I've thought this for a while, that whilst the GTD gets the full front end from the GTI, the rear bumper is bog standard Golf 7 (pretty much the same as an SE, GT etc). When those guys fit chromed tailpipe tips (as a lot of them do), from the rear (apart from the LED lights), the rears looks very similar. Would have been nice if VW had given us a honeycombed rear diffuser identical to the GTI, but with the cut-out on one side for the dual pipes. Having the different exhaust exits between the GTi and GTD would still have left enough differentiation between them ?
The Part that Graham showed is from the new R-Line models (not sure if we get that in the UK). So the question is, does this fit the GTD bumper, or is there a very slight difference in profile between the GTD units and SE / GT ones (if so it's so small as to be unnoticeable).
**edit**
Just answered my own question. Went onto the Ebay.de and there's quite a few rear bumpers from the R-Line models for sale, so I grabbed one of the better photos and compared it to a photo of the rear of my GTD (from a very similar angle), and the bumpers are a totally different shape as are the diffusers. So the R-Line ones won't fit unless you change the whole bumper.
