It's time that I updated this thread.
I've given up the notion of using mpg figures to accurately compare adjustments or mods, there's just too much variation in riding conditions and minor fill errors with this little tank.
I started filling at my local service station and because they don't stock the 91 octane that I usually use, I filled with 95.
That gave me lower FE ???
Because previous experience tells me 95 should increase FE, I suspect their pumps are a bit off, so I've gone back to filling further down the mountains.
I fitted the larger front sprocket and saw an increase in FE. Fitting the smaller rear sprocket hasn't improved on that so far, but it's only been one fill, maybe I just need to get used to playing the gears a bit better.
I'm not happy with the screen I'm using, I'll probably make a custom screen rather than use another universal type, maybe not as big at this one though.