Combine the Active Autowerke Exhaust SECTION 1 with a pair of Hi Flow 100 cell metallic catalysts and you have part of a winning combination for your BMW E46 M3.
DESIGN AND CONCEPT:
The Active Autowerke Exhaust SECTION 1 only comes into play if the E46 M3 already has a performance header already installed. One will experience a high smell of unburnt fuel. (due to the open exhaust w/o any catalysts) and development of a RASPY like sound of which the BMW S54 engine is notorious for with the BMW Stock Section 1 when equipped. This raspy like sound is a matter of engine sound harmonics at a specific RPM range, a sort of resonance that is very loud and noticeable when the engine is revving at or above 4,000 rpm.
With the Active Autowerke Exhaust SECTION 1 installed, the BMW performance gains are about the same as running the factory section 1. However, that's impressive considering the exhaust flow is also being filtered while running through a pair of 100 cell catalysts. The power and performance is still there.
Gone is the smell of unburnt fuel. A BIG advantage.
Gone is the RASP like sound. Another BIG advantage.