I would like some longer HIWIN rails and ballscrews for my x-axis, 9 feet or 108 inches. You list maximums as 78 inches.

Yes, however, if you are needing a length of the HIWIN specification rail longer than our 78" max length, then you can abut more than one rail together to increase the length of the rail. We do this for our long X-Axis travels on our Fabricator pro machine.