I have had Pirate do an extended seat on my GTS, and it is a good job.
I am looking for other seat specialists, who might do a custom shape.
In having Pirate do the extended seat, I did not realize that in trying to keep the overall profile the same, their usual practice of cutting down the foam and putting a thin gel pad on it leaves you with a saddle of only modest comfort.
I would like to raise the profile a bit, and have more support in the saddle. This requires some serious skill if you want to keep the saddles shape attractive. I had not realized that the standard seat has many surfaces/shapes/curves that really suffers when you start surgery.