I've got fibre glass LE lips on mine which is not lowered and you still have to be careful. Haven't had any problems with speed bumps, but you can't swing the front bumper of the car over most pavements i.e. when making a 3 point turn like you could before, and some steep ramps in car parks are now no go
I got my LE lips fitted and managed to trash them within a month in my works underground car park
I then drove the car for about 6 months making sure a new what was possible or not before getting them re-sprayed. So far so good