2002 A6 2.7t Quattro.
I think I have a boost leak and or plugged cats. What are your thoughts???????
Here is what the car is doing. When I accelerate the car stalls/hesitates/jerks at about 3000 rpm and will not speed up I can here a hissing/whistling/venting sound. If I try to lightly accelerate or use the cruise control to raise the speed I can get up to speed also if I down shift and keep the rpm's up it will make power but you can hear what I think is a boost leak. I used the fogger we have at work to find two leaks in the intake system. One was intake "y" boot and passenger boost sensing line to the turbo. (Not sure how long the banjo nut/bolt has been missing) both fixed. (Car was parked and not used for several months it had ECM issues.) Was planning on using the fogger again to see if I have more leaks. If I can take it home.
Why I also suspect cat is very poor gas mileage and does not seem to have power.
Thanks in advance for any help.

 

Found a leak on the drivers side Bi pipe going from intercooler to throttle body boot. There is a crack in the seam on the bottom.