I had simular probelm before when I was working on my FMIC. The boost would only go to a certain level and stop there. And I found out it was a leak from the pipe.
Hope it would help

 

where did you hook up the boost guage? if you have it hooked up at the FPR or anywhere at the manifold and you are seeing only 20 vacum i think there is something wrong mine is sitting at 50 or 60 during idle. i would look at the hoses under the manifold. there are about 3 or 4 of them. one hose which went out on my carwas coming down from the middle of the manifold.The hosemade a 90 degree turn, andit split at that joint and leaked badly, but only during boost. Main reason was because it is a rubber casting like most of audi/vw hoses, which means they have a seam. The easiest way to check this is build a pressure cap for the manifold. i know you can get them on e-bay but you can make one for about 10 bucks. i used a 3" pvc pipe link from home depot, a pvc pipe cap, and a standard air nipple from kragen (the nipple you use on wheels to inflate them ). Drill the cap slide the sucker through and pull tight, then clamp on to the throttle body and inflate. You will need a compressor for that, but you will find the leaks right away.
the reason for my thinking its a manifold issue, is the low vacum reading which is controlled by the throttle body. so that doesnt have anything to do with turbo pipes

 

Im sorry precision, i stop reading after vac and idle. 20in hg is normal (give or take 1-2 depending on altitude). If your seeing that much, YOU have a problem

 

acctually i retract my previous statement about vacum leak as you are holding correct ammount. the vdo guage is listed in in/hg so 19in/hg which translates to 50 cm/hm. but i wont rule out the hoses under the manifold.

 

You run a metric/bar gauge huh?

 

Ok so I removed and tested my DV just like in the PDF and its not working right.
Heres what I came across the DV is missing the o-ring thats on the bottom part.
Could missing the o-ring cause problems with pressure in the turbo system?

Now with the DV swapped from Forge 007 to OEM first gear is actually holding boost during launch 10psi unlike before that I was lucky to see 4psi.
Unfortunatly I still have that funny sound with nder boost.
Ive been sick with the flu so energy to do stuff isn't all there in between work and home.
I still need to get under the car and check all my hoses , vacuum and all intercooler pipes.
I must say all this input is very helpful.... lets keep it coming
ThanksEveryone.

 

Well over this entire peiod of time I've checked all of my lines.
Vacuum, IC,DP... I haven't found any cracked or torn hoses or pipes.

I remember thinking that the sound would be intermitent, like before the cars warm the noise wouldn't be there but after a nice drive it would start to make the ticking noise.
That had me thinking it had to be something that would expand and contract easily.

Now heres the reason its up again I was stumped on everything I had checked and remember I forgot the intake.
I check the MAF to intake connection &its fine but the pipe felt a little loose.
I tuged on it and it just slid off of the turbo [>:]

Here are some pics and a link to the video.
Do you all think Im missing a clamp aor something?







one sec on pics Im resizing..

 

Thats how the connection is made. There isnt a clamp for it

 

Then Im lost right now.......would anyone be able to direct me to a DIY on compression testing the turbo system?

Thanks