Falcon fg2turbo diff ratios with zf auto

what's ,good,better overall experience? 3.23,3.45,3.73,3.9,4.11

At the higher end of the spectrum you will have better cruising economy, at the other better acceleration.
Whether this would be noticeable in anything other than a side by side comparison is a moot point.

had a roadrunner in canada,4 speed manual and it came with 3.93 gearing. swapped it for a 3.23 dif and the acceleration went down but each gear was longer, ie 2nd was good for 85 mph. economy improved from 12 mpg tp 19 mpg which is what i wanted as we were using the car for cruising not racing.remeber to get the speeo drive gear out of the g/box it matchs the diff ratio.

Just stick with standard ratio. I had an FG2 G6E Turbo and it was certainly fast enough. I don’t think you would gain any noticeable difference in changing the ratios. And the standard setup gives an excellent spread of ratios with top gear 100km/h at 1600rpm.

The problem with the FG Turbo range is getting the power down. Granted the G6E Turbo has an open diff but the XR6 Turbos with the factory LSD I drove were no better at getting the power down. The rather rubbish stability control program cut power far too soon and aggressively as well. But by god once it gains traction they are a very very fast car indeed. Many people with proper performance cars were very surprised at the mid range rolling acceleration

And ultimately the traction issue is what stopped me from having mine performance tuned.- In my opinion, first money needs to be spent on upgrading the power down aspect. Good quality LSD and wider rear tyres.

I have a bf sw with zf fitted and the standard sw 3.23 diff ratio instead of the 2.73 fitted to zf cars, It goes really well but 1st is a bit of a joke and its heavy on fuel, I think a 2.92 or 3 would be better compromise.

Diff ratios are very carefully chosen by manufacturers, what are you trying to achieve by changing it?