Am i right in thinking that the width of all four tyres has to be the same or can two be wider than the other two?

I believe all the wheels are the same width, hope this helps

If you plan to use the 17" street pack alloys, the tyres must be 205/40/17 to keep the speedo in check. If you place a smaller tyre - example a width of 195, then it simply wont fit.

Also, i don't see why you would want a larger, or smaller tyre on the front wheel drive car If you had a rear wheel drive car - then yes you would place wider tyres on at the rear. But in a FF car...is there really any point?

Personally I'm gonna be fitting larger profile tyres at the rear, I don't feel the eibach springs have dropped my car completely level at both front and back, so I'm wanting some slightly bigger rears to fill the arch a little more, will also compliment the spacers when I get em on.

MOEFOE11.... as long as the wheels on the same axle (both front, or both rear) are the same size then you're fine. But the front don't need to match the rear.

As MARK W.K. mentioned, it will undoubtedly knock your speedo out slightly, but if we want to get really specific about it, your speedo is already reading faster than you're actually going, this is done by law in the UK to slow everyone down a bit.... you will notice this if you have a sat nav reading your actual speed, or if you see any of the clever street signs that show you your speed.... they will always read slower than your actual speedo. So putting bigger sized tyres on your car will actually make your speedo more correct.... technically...

But again, the difference it make is so absolutely tiny, its not even worth debating.