would have to see the figures to know what your talking off but have seen ecu sometimes call for desired maf up to 1200mg/I depending how egr has been deleted, so if you saw
desired maf 1200mg/I and actual maf 600mg/I this may well be normal.
your maf in other graphs looked ok but to check if you can open in excel and just chart actual maf and actual boost and then create new column boost/maf your answers should be around 2(1.8-2.2 still normal from what ive seen on here)
so example 2348mbar boost divided by 1.8 =1304mg/I maf
or 2348mbar boost divided by 2.2= 1067mg/I maf
but ideally 2348mbar divided by 2 = 1174mg/imaf
this sort of thing
if values are way off 1.8-2.2 something is amiss maf or boost values
back to the engine braking
your vnt % are going to 75% when off throttle, this looks still original (hence why I was asking how the egr delete alters vnt or not )and was something to help pressure build up behind turbine and egr gas get pushed through cooler and egr valve.
with egr now blanked the pressure build up behind the vnt may be enough for you to feel a restricted breathing.
if autolusso are willing they could reduce your vnt% in area of map where egr was active.
for example 50%vnt in the 0mg fuel area.
I have mine around 30% vnt and possibly too low(may lead to higher compressor oil seal leakage)
if you want to test yourself , you can pull off the vnt vac hose to the actuator and plug the hose with a golf t or something( make sure doesn't dangle down into road or go into rad fan etc).
this will leave your turbo at min spool position vanes fully opened.
take it for a drive(you wont want to go far), it will sound different bit more bassy, will have serious low power, but if you lift off and coast in gear and the engine braking feel has gone this may well be your issue.