Here is a dance-off between the stock exhaust system for the BMW M4 and its aftermarket potential replacements from Hamann and Akrapovic.
Without a doubt the stock exhaust is the more tame one, while the other two are loud and with a deeper growl. The loudest and deepest sounding of the three is the Hamann exhaust, but some may like the Akrapovic for its more civilized sound. Unfortunately the video reviewer doesn’t take the three cars on the road and record the sound, a more realistic comparison.
A good exhaust system and its sound stands out through a series of downshifts, tunnel drives and backfires, for example, so a more extensive test drive is in order before deciding on what the best exhaust system for the M4 is.
We haven’t had a chance to experience the Hamann system, but we did spend a few minutes with the Akrapovic unit at Nurburgring last year. Sadly, in a parking lot also.