We just installed our Fabspeed Performance Package with ECU Tune on a BMW E92 M3. The customer was leaving the stock muffler on the car but didn't know if it would sound much more aggressive with the OEM mufflers, well he was amazed by the sporty sound difference over stock and loves that he can drive it every day with no sound issues. The installation took about 2 hours to everything and bolted right up like OEM.

Removing the stock restrictive 2ndary Catalytic converters, replacing the primary Cats with our 200 Cell Sport Cats and flashing the ECU really makes a noticeable HP and Sound Improvement throughout the RPM range. This is a required upgrade on all these cars. You can view Dyno results on our BMW page http://www.fabspeed.com/BMW.html

The customer loves the deep sound and power increase of the exhaust, and the ECU tune really complimented the rest of the exhaust upgrade. PM or Email me if you have any questions and I can offer a Fabspeed discount to all 6speed members.
Thanks,