No real harm in doing it, you may not notice too much difference on the road though (unless you're a road speed freak!!!
) and you will lose the steering lock.
What are you trying to gain by doing it? If its for quicker steering, you could try jacking the back up a touch - it does create a similar effect on the steering and can be easily tweaked (more variance) or put back to original rather than moving the steering head.
Tim
[Edited on 14-8-2005 by Rattler]