Possible missing boost UrS4 help please

[iain.atkinson at tesco.net]

Several questions i am afraid folks.

1. What do other people see on there UrS4/6 stock ecu no other mods, i am getting 1.7 bar max, (and saw once 1.8) sjm's site suggests it should be 2.1bar, i am at sea level btw.

2. In my search for this missing boost, i have done the following
replaced michelin man hose
replaced wgfv and diverter or bypass valve
pulled the codes, nothing wrong there
checked all the other hoses for splits and lose clips (non found) and replaced several rather tired hoses clips along the way mostly on the crankcase vent system.
Checked wastegate diaphragm for splits and tears (non found).

Car drives fine no bucking or sudden loss of power, pulls fine all the way into the redline if i want it too. I have tried making a leak detector to plug into the maf hose but how much pressure should i pump into it, garage airline ok??? 

Only other thing to say is that when i had the wastegate cap off under the spring seat i found a very thin nut, obviously put there by someone to improve things.

tia

Iain