Cheers for the comments guys.
To answer a few questions in no particular order:
Lowering, maybe, but not just yet. Might go for a gentle drop sometime in the future.
The wheels, well I wasn't too sure whether they'd suit the car before I put them on. They do look smaller on the mk6 than they did on the mk5 and the rear arches of the mk6 must be wider than the old car too as they sat pretty flush on the mk5 but sit in slightly on the newer car. They look better in the flesh than in the pictures but I may well change them in the future for some Monzas. Mostly because Monzas are easier to clean! At least with some different wheels to standard the car attracts a bit of attention and people don't immediately think it's a company car.
Yes, it did come with 17s. I wanted a pretty standard car so that I could upgrade bits over time as finances allow. I would have happily got one with 18'' Shadows and sold on the BBS but got the best deal on this one.