2000 up valkyrie seat $100 most sites, then utopia backrest,
http://www.utpr.com/valkyrie.html, can be found used for less.
That's my current setup, been very happy with it. the seat is awesome.
back issues, check out
www.Drbookspan.com she is the top of the line of research and everything filters down from her to medical cartel. just reading and following her site fixed my problem.
Dr. Bookspan is an award winning research scientist who developed medical
and training methods that are used by physicians, trainers, military,
injury rehab centers, athletes, and you, to make life and exercise healthy again.