hey guys. im thinkin bout gettin sum 15" alloys (upgrading from 14") for my 1.2 64bhp fabia comfort. thing is, dunno how much it will affect the perfomance because as u can see, its not the most powerful of cars with that amount of bhp. any thoughts?

If you stick to something like 195/50 X 15 you should be okay as it is the rolling radius of the wheel/tyre that affects the overall gearing. There are plenty sites that give you guidance into which "+1" or "+2" wheels/tyres combinations are similar in rolling radius to your original wheel/tyre combination.

The 1.2 12V Sport came with 15" alloys from the factory , so you should be okay , power wise. I think when you get up to 17s or 18s then you would start to struggle , unless you bought super-light wheels.