Therein lies a real saga....
Spoke with 3 Holden service centres, they all said they could do it. I took it to the closest - Village motors at Petrie. They got it well wrong... Then told me it can't be done. So i checked with 2 other Holden service centres, 2 auto sparkies and a specialist tuner. they told me it can. I did my own research, and even found holdens own tech 2 guide on the web, complete with how to enable cop mode, what ppm settings for which wheels, and how to enable the police calibration mode. Took it to Village motors and they said "We won't use anything that we don't get from holden ourselves" ....
Which could be understandable, they wouldn't want to use some failures half arsed guide and get it wrong.
Anyway, I ended up emailing Village motors tech directly, sent him what I found, and had him check it out.
They called me up and said bring it in thursday we've found out how to get it done....
Results tomorrow maybe....
Anyway - I'm not changing the BCM at all, just re-calibrating the dash. So shift points / road speeds will remain the same as far as the BCM is concerned. Theres no feedback from dash to BCm that I need to worry about.
Oh and how does it drive with the well modified gearbox ? Ummmm - dont flat shift into second unless you want to wheel spin for 30 yards at 60ph.
Spool it up against the torque converter, ease off the brakes and it will smoke off the line. The last bit of retardation from the front brakes is all it needs to break the rears free. Step off the brakes fast and it squeaks and gits. Hard. Magic. Should have been the factory diff. Economy seems better at city speeds too.