Akrapovič® (14-18) BMW X5/X6 M Exhaust Sound Kit

An exhaust system is like a musical instrument, converting rough pressure pulsations from combustion to sound, which defines the overall character and appearance of the vehicle. Akrapovič is taking the sound of the exhaust system to the next level, while a team of NVH (noise, vibration, and harshness) engineers carefully tune every tube, muffler, and tailpipe to a specific vehicle. Prototypes are designed with attention to detail to extract the best-possible sound potential. Every prototype is measured with state-of-the-art measuring equipment, which measures the sound of the vehicle’s interior and exterior.

In addition to sound, many other vehicle parameters, such as vehicle speed, rpm, exhaust gas temperatures, and vibrations, are measured and correlated with the measured sound. Data are processed in the frequency domain and converted to 3D graphs, also known as colour maps. Every colour map represents an exhaust system’s sound signature, its identity card, where the sound level is presented in dependence on frequency and rpm.

The team of engineers spends countless days searching for the perfect balance of sound, navigating between sporty and comfortable, refined and rough, and quiet and loud. Prototypes are constantly being improved through on-road tests, dyno testing, acoustic transmission loss, flow testing, and simulations until the required sound perfection is achieved. The sound itself is ultimately still in the domain of the engineers’ subjective judgement, but is supported by objective sound engineering data. Every step in the creation of an exhaust system, from development to production, is careful planned – to the last detail and to the last millimetre.