'01 A6 2.7T 95k....Not boosting as high as normal...the check engine light came on the other day, P1136 code said engine was running lean. I found a small vaccum hose leak near wastegate and fixed it today (CEL is still on though). Stock boost is normally around 8-9 psi, but I am only getting 6-7 psi. Also, the boost seems to climb more slowly than it has been, and it occassionally goes into limp mode (only 3-4 psi). The turbos were replaced about a year ago with all new blue hoses. There arent any other symptoms, no weird noises. Any ideas?

 

I was having the same problem with my 1.8t and it was a plugged cat. Bought a test pipe and car runs great.

 

how do i test to see if a cat is plugged?