Lumbar support: Exec. alt. for $30. Long time "bad back" was in bad shape from working on the e28 before 10.5 hr drive to FL in '89 525 w seats in exec shape. Bot "Flex-N-Rest" open weave adjustable support with two straps to control lumbar curve. Support fits e34 seat very well. Wife now using, it was her car, w/o complaint and I need to get another.
Big accident on I 95 added 5.5 hours to drive. No problem with back but great surprise that back improved greatly, including slumped shoulders that had become worse over several years. Standing straight and back continuing to improve.
How bout $23.00 from Crescent.