If you have access to a compressor with a pressure regulator, I would do the tennis ball test. It will literally take 10 mins to setup.

The other suggestion, if you have access to vag-com, would be to log the actaul boost vs. requested boost numbers and possibly fuel trim numbers as well.

I am sort of having similar issues as you except that I am chipped. I hope to make some progress this weekend.

 

I'm going to try that test and see if I can figure anything out. I read through that DIY and it said to tighten the tubing around the ball to keep air from leaking through do you have any suggestions on how to do that and how to keep the air from leaking back out through the hole in the ball? I don't know if I should just use a large hose band around the tennis ball and seal up around the compressor hose with electrical tape or what.

I may have to use a normal bike pump too I'm not living at home right now and have no compressor or tools beyond a few screwdrivers and a drill. Don't know if that will work or not. If it won't I'll have to take a trip home for a day or two to use a compressor..

 

I doubt a bike pump will work because the flow will be insufficient (atleast thats what I've read) but I'm not sure.

The holes I made in the tennis ball were very small, about 4mm D, because I used a blower attachment on the compressor hose with a small nozzle. I forced the nozzle into one of the holes and it sealed up enough for me. The tennis ball is nice because it is small enough to fit in the TIP and large enough to make a seal with the factory c-clamp. Disconnect the tube from the airbox, put ball with holes in end of tube, and use factory clamp to tighten tube around the equator of the ball.

I found it useful to have someone charge the system for me while I listened for leaks throughout the engine bay. Just make sure you dont overpressurize the system!

I dont know if your far from Reisterstown, but I will probably be doing this test on my car this weekend.

 

Yeah I'm at the Jersey Shore I won't make it back. If I was home it'd probably be worth the trip considering I live in Annapolis. I'll have to see if I can get my hands on a little compressor for the weekend. This has really been bugging me and I refuse to try to mod my car until I get it running in top shape.
The turbo and engine were both replaced at 72k (my Aunt blew the engine) and it's up to 127k now. I'm a little disappointed they didn't just do the whole system but I guess that's a little too much to ask for a warranty fix. I'm almost hoping it's a leak at this point so I can get it fixed and drive the way the car is built to be driven. It's really choking my power and my nerves!

 

I did the leak test this weekend, and found a small leak from the cam seal tensioner gasket. I replaced gasket and now the boost seems to be a little more lively. Still dont know if I'm totally satisfied. I plan to do some data logginf with the vag-com before installing the N75J