Well, not to pour oil on the fire here, but extensions MAY cause fender cracks. I had two different kinds of extensions on Rio. The first one cracked the fender. I put the second one on with the braces that Preston provided free (thank you, John) and when I sold him, the fender had not cracked. I think it is a matter of a combination of a number of factors - length of the extension, whether you hit something on the road (trash), and perhaps something about the design of the fender itself.
Rather than poo-poo what others are saying, just be warned that there is a possibility that your front fender may crack with an extension. You take the risk and you may have no problems whatsoever, or you may wind up replacing your fender.
Mesquite Bob