I just picked up this brush guard for my 2001 vitara, have never seen one like it before.
does anyone know if it is a factory option or a after market add on?

There was a factory option that looked like that - is it made of flexible polyurethane?

this fairly rigid fiberglass or composite plastic material.

Post up a picture when you get it installed.  I'd like to see what it looks like on the truck since I've never seen one like that.

this fairly rigid fiberglass or composite plastic material.

Possibly an aftermarket knock off or custom replica then - Suzuki did offer a guard like that - you should be able to find it here

Front guard, wide - made of hard polyurethane without metal insert

99000-990YB-650 - Silky Silver Metallic
99000-990YB-691 - Primed
99000-990YB-651 - Unprimed

Interesting - the link I posted shows different part numbers to the ones in my brochure.