Here's my theory. There is a known problem with the "fly by wire" accellerator pedal with all BA Falcons. We have done almost 30, and mine is getting done tomorrow. There is no loss in performance, all that happens is when you go past, say, 1/4 throttle, the engine light comes on, and "usually" stays on until you stop accellerating. It does log a code in the ECU, a quick hookup with a PDS/WDS will verify this. I would say its pure coincidence that the engine light is coming on after the exhaust was done. Give your dealer a quick call, and ask if there has been any problems with the engine light coming on while accellerating. If you have no luck with that, let us know..... that's what I reckon, will be interesting to see how close I am!