Dave at AZC is very good to deal with apprently.
Some ehaust shops will make a set up for you, but don't expect it to be cheap.
Kenmeri in Japan also make extractors, but you'll very, VERY deep pockets...
Try doing a search for the name 'Issac' (not the username of the recently joined member).
There was a VERY interesting thread about this Issac in NSW who occasionally sells 2 seater's...
Might need to amend the RS30 body/chassis info, Gav.
Early RS30 body shells are vertually the same as the later model S30 bodys (well there are the same), but the later (post '76?) RS30 bodys have taller rear strut towers - they are actually left over US-spec 280Z bodys...