I done my SV's seat, and made my own cover. I scooped it out with a foam saw (we had an upholstery shop at work)and made it the shape of a human butt instead of a pavestone with padding. center cut it and installed a bicycle seat gel pad, covered that with 1/8 high density foam, and a 1/2" low density foam on the outside, to smooth the form of it out. It actually looks pretty geed except for my frankenstien sewing job on the cover
Rides way better though. used to feel like you were sitting on a 2X4. It's still not quite gas station to gas station comfortable, but I can stay on it 100 miles at a time, and with the gel, you can throw a zip-lock bag of ice on it for 5 minutes at a gas stop and chill your buns.