The only stated difference in the CLA45 Order Guide for the performance exhaust is "enhanced exhaust sound." The variable vane modulation and the 4 tip outlet design are common for all CLA45's. On many newer sports cars, the "enhanced exhaust sound" is a feature in the car stereo system to artificially make the exhaust note sound better inside the car, not louder outside. Porsche, BMW and several others are already doing this. I don't think we have enough details at this time to definitively say whether this is electronically enhanced sound through the stereo system or a mechanical difference in exhaust hardware components. I would strongly suspect its the electronically enhanced sound. We will likely need somebody with an A45 to step forward or perhaps reach out to AMG and see if they will provide an explanation.