you sure it isn't the 17" wheels? the 1.4 8v hasn't got much power as it is, then with 17" wheels you are adding gearing to the car?
Ive got 16's on my 1.4 8v and its lowered and I dont have any problems. Still on the gearbox it left the factory with and no signs of crunching/whining etc.
It definetely could be the 17's that are an issue.