Hi all,

Does everyone that has a 425 fitted to a V8 (351C) have a feed back system, is this the only way of getting reasonable economy, maybe more than 150km from 95lt usable..

The way I see it is if the AFR (16.5) is correct across the rev range all is good, wouldn't any feed back system not work or lean off the supply.

Just not sure how to improve economy.

16.5:1 far to lean. Even more so if you are using a regular AFR meter that displays on the petrol scale.
I'm surprised you're not having major back fireing problems.

too lean will cause poor economy just as much as too rich

All a feedback system is going to do is aim for stoich at cruise.