Diff ratio change for a zf auto

[Wolfinsheepsclothing]

hi Chris/Theo i've been looking into changing my diff ratio in my xr8 zf box,2:73 to 3:23 but my local performance workshop inquired via Rob from Herrods as they haven't done one yet,apparently Rob said that zf needs the sct upgrade which hasn't arrived yet,as it stuffs up the gear changes without the tune,but there's been a few aff members who say it works fine,one said he raised the rev limiter by 500rpm,what do you knowledgable fellows reckon,any help will be appreciated,cheerz Geoff

[XTT747]

I'd imagine it is very possible considering it isn't the "Shift points" which get changed, merely the PCM's final drive ratio...