2.2 mk1 boost figures

[Monkeyfeet]

Need some thoughts on this please. Help get me straight on my next step.
Car runs fine generally, smoothly & in mpg low forties ( normal readings for our use) but sub 2k pull has gotten quite poor, down changes required uphill. Plenty of go over 2.2k ish revs. Don't get me wrong, it'll cruise on a light throttle very nicely and is still very driveable. In fact it's just come back from France, loaded up as usual and it still managed 43mpg. However it's always been quite gutsy until now. (Occasional eml/esp/etc when floored for too long)

So far I thought maybe the dreaded leak in the vacuum circuit to the turbo - so today removed pipework from electrovalve to turbo for a peek. Original but good nick, no signs of perishing whatsoever in fact.
Went for a run and monitored "Turbo pressure measured" and "Turbo level setting" values on the Lexia.
Low throttle they were pretty similar but sub 2k ish revs with the throttle floored (value also checked) the "turbo pressure setting" figure was substantially higher than "turbo pressure measured" figure. So it appears I'm not getting the required boost level at lower revs. If there was a problem with poor vacuum then I should see too much boost, not too little, surely?
Watched the turbo electrovalve too. Opened up when throttle pressed to match "pressure setting" value increase.
Swapped electrovalves, swopped electrovalve ports (does the outer port have a vent?). Got a good suction hiss when I pulled the pipe off. Not sure on size of vent though.
Disconnected vacuum line from EV o/p to turbo and warning lights almost immediately after.
Previously checked vacuum level - good at around 100mB abs. Figures from measured and setting match at higher revs.
Had new oil, oil, fuel & air filters in May.
Only vacuum pipes left in circuit are to the turbo and swirl valves. (all others blanked off/ removed)
Lazy turbo?? Too much vacuum?
Thanks