I have the Seat Concepts low seat on my 570 and the OEM cover stretched easily to cover it with no additional material needed. Looks great, but the low SC seat is pretty thin as far as padding goes, I definitely feel the seat pan on hard hits. I just sent another OEM seat off to Renazco to have true long distance seat made, I will report on the difference after Christmas when I get the Renazco back.
On the fuel tank post
seeing that made my day after a frustrating day of Efing up my R1200GSA trying to do a simple oil change.. I really shouldnt be allowed to handle tools