i have an A31.6 2001 MODEL.RECENTLY I VE PUT THE ENGINE OF S3 99 MODEL WITH WITH GEARBOX BRAKES ECU ALL THE CONVERTION.MY PROBLEM IS THAT WHEN I PUSH IT AND PARTICURARLY WITH 4TH GEAR IN 4000TURNS MY CAR SLOW DOWN WITH LESS POWER AND WHEN I PUT THE DIAGNOSTIC IT SAYS "MAXIMUM PRESURE EXCEEDEED"THE ONLY THING I HAVE CHANGE TO THE CAR IS THE EXCHAUST THE SECOND AND THE LAST PART 62.5 HANDMADE.THE CATALYT IS THE S3 I DIDNT CHANGE IT.PLEASE I CANT FIND THE PROBLEM.IS IT A PROBLEM WITH ECU.NEED A PROGRAMM?

... and it is most likely something that is part of the boost control system like the n75 valve or the by-pass valve or the vacuum lines to/from those valves.

Kirk