Yes, I have. We also have a fitting guide for that. They are standard on all 1.6FSI in Germany (or even on some, maybe depending on model-year!). I don't know anymore. This material is soft so you can hit the kerbstone.
But the car will not really go faster but this upgrade solves a problem with the brakes, if it is wet and you are fast on the freeway. They (the brake discs) will not get this much wet as without these spoilers and so you can brake quicker (the brakes are working faster, when braking).
needed parts: (this is really a cheap upgrade! For less than 15 pounds)
1 x 8Z0 853 887 A Spoiler 3.00 €
1 x 8Z0 853 888 A Spoiler 3.00 €
6 x N 906 513 02 Schraube 9.60 €
4 x 8Z0 807 300 Spreizniet 1.60 €
prices are from 2004 and plus additional tax.
The fitting guide with images, if you are registered(but I uploaded them):
http://www.a2-freun.de/forum/showthread.php?t=16160
You don't really need all the 6 N906... longer screws, because the old one will fit. So buy not more than 4 of these screws.
But there is one more much more efficient upgrade! Buy the tunnel-cover from the middle of the bottom of the car from the 1.2TDi plus the slim spoiler ! This makes the car faster/more MPG and it leads to more downforce.
For that you need:
8Z0 825 229 (21,30€)
8Z0 825 211 slim Spoiler 15,61€.
Dazu die passenden Spreiznieten (expanding rivet) 8z0 825 267 each: 0,73€ (three needed))
And this upgrade starts here:
http://www.a2-freun.de/forum/showthread.php?p=650443#post650443