I agree, my back does get achy after a long ride... I know one cube that has bride seats I think... Otherwise everyone else that has done anything has been clazzio seat covers. I think they add a little more, but not much.
I looked at Versas seats to see if the seat rails were the same, they are not, I think the same with the juke, but I am wondering how much the seats can be taking apart and rebuilt to fit universally... Juke seats would be sick!