I just took the Z4M for a spin. It drove fantastic. Sorry about the sound quality. I left the closed cover on the Go Pro so it's hard to hear any of my commentary or the sound of the car. The car is extremely quiet. With a factory exhaust there will be no way to know this car is not stock (except for the MASSIVE POWERBAND!). We will be dyoing Alex's Z4M later this week so stay tuned!!