This BMW 535i E60 with a twin-turbo petrol engine and MSD81 ECU had a larger-diameter exhaust section fitted after the catalytic converters. The catalysts and oxygen sensors remained installed, and the tests used 98 RON petrol. The video quotes factory output at about 300 hp and gives an initial dyno reading of 371 hp and 445 Nm after the exhaust change.

Calibration and engine operation

The video gives a post-calibration result of around 350 hp and 505 Nm. Since the stated initial dyno reading is higher than the quoted post-calibration result, these figures do not establish a reliable gain from a like-for-like dyno comparison.

Engine hesitation was noticed under high load. The video recommends checking the spark plugs and ignition coils, but does not confirm that this work was completed. The ignition system’s condition should be established before further load testing.