Scirocco Central

Also black shoe polish, the one with the foam end works really well to brighten dull black rubber.

Gummi Pfledge is great, use it on the lip seal to the electric windows and see how much faster they move.

Its definitely a bumper off job, use a small screw driver to lift the tabs you will aslo need to remove the torq screws fir the top pat of the grille, take you time as the tabs can be brittle.

i have on a previous car but to be honest it did naff all. Idling a diesel isn't great anyway (in my case). an italian tune normally work well, get the engine hot a give it some beans.