tailor made seat

Guys ...is anyone EVER made the seat thicker like as thick as to be level or there abouts with the rear seat.... as ma muscles in ma legs are very sore especially behind ma knees.... a had seatica pains in ma legs last nite fae Cramps...never had this before....does anyone know of anywhere on one who would do this....as riding aronund sitting on a pillow folded in halfs not COOL....mabozzar,,,,,,itchy