Hi Jason
Probably I am too late for you to even bother any more, but I may help you somewhat.
My father had his name from Aalesund, and his father had the same name as me, Martin Ystenes. His father was Arent Krestoffer Karlsen (?), who took the name Ystenes in the late 18 hundreds.
Arent had several children, and all of them - except my grandfather - left for the USA. As far as we know, none of them kept the name Ystenes, but changed to Ness and Arntsen. My father have much contact with several of his American relatives who live in New York.
Because both my grandfather and his wife died very young of tuberculosis, they got only one child: My father. His descendants are - as far as we know - the only ones left in Norway that descend from Arent Ystenes.
Most Americans with the name Ystenes come from Hardanger, a place that is now called Ystanes. Ystenes is now more or less a parking place on the main entrace to Aalesund just before entering the center og the town. There are approx. 100 persons in Norway with Ystenes as family name, of which approx. 10 has got the name through my father.
Martin
(Home page:
http://ystenes.com)