I have 17" Khans on my 16v with 205/40's. I have G60 arches, and they have been rolled a little. My car is also lowered on Koni adjustables, but then I raised it a bit because I want to be able to fit 5 people plus drive over those f***ing London speed bumps, without rear arch scraping.
It all works, the ride height is very cumfy (still handles much better than standard), and there is no doubt that the wheels are simply the dog's sacks! I couldn't imagine my car with 16's, if u ask me, the difference is huge, and with a discount like that, u have to get 17"s on there. I'm still waiting to get a digi photo of it so u can see what I mean.

DONT JUST SLAM IT! My advice is to get adjustables, but u better speak to someone like premier power or elite motorsport who will tell u the possibilities. Oh yeah, on the downside= i have lost some full lock, and the power steering system seems to struggle to turn the wheels at slow speeds.
H.