UPDATE!
Been a few months since installing the LSD, having changed the oil, found there was still clunking at the back end.. being the rear top mounts being absolutely ficked!
Changed them out for E46 top mounts, no more clunking
Also seems I've lost a race prep job i'd been doing at the weekends, Oh well... leaves more money for going to a drift day (FINALLY!) Hoping to be up in May providing it doesn't clash with my exams with Mazdachris.