What happens when you drive without one ?
The handling is different, and until you notice the difference is not to your liking, you really dont 'need' one right away.
However, you could wreck the car.
Say whuh ?
Yes. You have become accustomed, over years of driving this car, to the handling properties it had with the sway bar. You may not even know all it's doing for you nor under what driving situations it serves it's true function.
You will become rudely surprized one day, without fore-warning, when driving in one of those situations and the car doesn't go where you tell it to.
This instantaneous surprize lack of response is horribly dangerous. You'll have miliseconds to react and, depending on circumstances, could easily wreck it.
The solution ?
If you intend on leaving it off for a long while, Go out and practice some 'sway bar moves'( cornering, lane changes, both accelerating and braking ) with it to acclimate your sub-concious to the new properties of NO sway bar. ( a new Ford one is only $ 138.00 )