I would only use an OEM battery. They're construction is better then most of the aftermarket ones. I think VW uses the same supplier (they look the same anyway... same handles, same translucent white plastic, same plastic sticker over the fill plugs) and my TDIs original battery lasted 5 Michigan winters! It could have gone another year easily but I replaced it with an aftermarket... I now wish I had gone OEM. (not to mention that the battery "installer" broke several plastic bits under the hood)
My SDL has an OEM battery, and it adds so much to the show under the hood
Can you get those MB windshield stickers at the dealer?
-Jason