Sounds like your Synchros are wearing.. chuck sum lightwieght shockproof (blue liquid) stuff in your box .. it fixed my crunching.. =)... If u wana get ur synchros changed it costs you the labour of pulling apart the box and putting back in!.. mite aswell replace anything else damaged while its out and opened! Im suprised its a 6 sp STI box and its having these probs.