I put a Corbin seat on my 2008 GS Spyder. It even came with a built in gas door. I always thought it was necessary to replace the OEM Spyder seats. I did it on six out of seven Spyders over a 15 year period.

I am one of the few who "liked" the Corbin. The "likers" say the seat is firm. In 36,000 miles it never broke in much different from the day it was installed. It was definitely an all day seat though. I went on many excursions with that Spyder.

Never had an Ultimate seat. There are many comments from people who purchased them. They were all good. We used BRP upline seats. Four of our replacement seats were "comfort" seats and on my F3L I put on a BRP Cannonball seat.

Seats are a very personal thing. I also recommend a thousand miles on the OEM seat before making a $500 to a $1K plus on the upline seat. Linda actually liked the OEM on her final F3L, so that was the only seat we never "upgraded" on.