17" and low profile - nice difference!
 

Just to add my 2p's worth...

Have just splashed out on some Prodrive WRC1 17" wheels with 215/40 17 F1s (did have 205/50 16 F1s). Car feels MUCH less squidgy and more postive on turn in now without any ride probs/harshness - good mod if you can afford it (and you can get those 335mm brakes on too!)

Mark