hmm I feel a hell of a lot better about doing this then. I may even get it in quicker than I'd initially intended. I spoke to Cmac engineering in Sydney and they said it wouldn't be too much trouble to take a crown wheel out from 113 to 114mm to match the Kaaz (assuming that I don't already have a 114mm ID crown wheel in the other box which is possible) and it shouldn't be more than 200 bucks. The alternative is to source a 114mm crownwheel and pinion separately. All the Polo Gti boxes have the same final drive but it may be that early Golf 02J boxes with the 114mm crown wheels will fit which would open up the chance to change final drive ratios but I haven't really looked into that. The rebuild kit for the diff from MD Spares in Melbourne was quoted at 450 bucks so that will be the next thing to get my hands on and then decide if the LSD rebuild is something I can tackle or if its a specialist job.