[WhiteWalker]

Recently installed a Meistershaft GTC on my '11 550i Dinan S2.

Under medium+ and steady throttle-- 5th and 6th gear , the car delivers a POWERTRAIN MALFUNCTION since installing my exhaust.

The boost seems to vanish and the car is not lifeless, but certainly running with significantly less power.

Recently had it at BMW where my mechanic advised of a potential vacuum left open when the new exhaust was put on. It was supposedly corrected and I also upgraded to Dinan S3.

First time out of the shop where I had the room, same result Powertrain Malfunction.

Any advise or thoughts would be appreciated.