I modified it myself, it's too difficult to do, also their a sources that will take your OEM seat and do the modifications to your specifications.
Here's my write-up including the other sources, I personally have seen the work that great day to ride has done, and I would recommend his services, and he's very reasonably priced as well.
https://www.ninjette.org/forums/blog.php?b=8352
Also other DIY projects from my blog,
https://www.ninjette.org/forums/blog.php?u=18557
If you find yourself in my neck of the woods, we should hook up, a lot of pretty back roads around here for sure.